Wikipedia

List of transitional fossils: Difference between revisions

Browse history interactively
← Previous edit
Content deleted Content added
VisualWikitext
m Reverted edits by 72.20.183.126 (talk) (HG) (3.4.12)
rcat
 
(One intermediate revision by one other user not shown)
Line 1:
{{Afd-merge#REDIRECT to|[[Transitional fossil#Prominent examples|List of transitional fossils|10 January 2023}}]]
{{Short description|None}}
{{Use dmy dates|date=August 2020}}
{{Paleontology}}
{{dynamic list}}
[[File:Archaeopteryx lithographica (Berlin specimen).jpg|thumb|right|Possibly the best known of all transitional fossils, the Berlin specimen of ''[[Archaeopteryx lithographica]]''.]]
 
{{R with history}}
This is a partial list of [[transitional fossils]] (fossil remains of groups that exhibit both "primitive" and derived traits). The fossils are listed in series, showing the transition from one group to another, representing significant steps in the evolution of major features in various lineages. These changes often represent major changes in morphology and anatomy, related to mode of life, like the acquisition of feathered wings for an aerial lifestyle in [[birds]], or limbs in the [[fish]]/[[tetrapod]] transition onto land.
{{R to section}}
 
[[Charles Darwin|Darwin]] noted that transitional forms could be considered [[common ancestor]]s, direct ancestors or collateral ancestors of living or extinct groups, but believed that finding actual common or direct ancestors linking different groups was unlikely.<ref>Stauffer, RC (1975) Charles Darwin's Natural Selection; being the second part of his big species book written from 1856 to 1858. Cambridge: Cambridge University Press. p. 236.</ref><ref>Darwin, C. R. 1859. ''On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life''. London: John Murray. p. 187.</ref> Collateral ancestors are relatives like cousins in genealogies in which they are not in your direct line of descent but do share a common ancestor (in this case it is a grandparent). This kind of thinking can be extended to groups of life. For instance, the well-known ''[[Archaeopteryx]]'' is a transitional form between non-avian dinosaurs and birds, but it is not the most recent common ancestor of all birds nor is it a direct ancestor of any species of bird alive today. Rather, it is considered an extinct close evolutionary "cousin" to the direct ancestors. This may not always be the case, though, as some fossil species are proposed to be directly ancestral to others, like how ''[[Australopithecus anamensis]]'' is most likely to be ancestral to ''[[Australopithecus afarensis]]''.<ref>{{cite journal | last1 = Delezene | first1 = LK | last2 = Kimbel | first2 = WH | year = 2011 | title = Evolution of the mandibular third premolar crown in early Australopithecus | doi = 10.1016/j.jhevol.2011.01.006 | pmid = 21481921 | journal = Journal of Human Evolution | volume = 60 | issue = 6| pages = 711–730 }}</ref>
 
==Nautiloids to ammonoids==
{| class="wikitable" style="margin:auto; width:100%;"
|-
|+The ''[[Nautiloids]]'' → ''[[Ammonoids]]'' Evolutionary series
|-
! Appearance
! Taxa
! Relationships
! Status
! Description
! Image
|-
| >500 Ma
|
'''Subclass:'''
* [[Nautiloidea]]
|
|
|
| [[File:OrhtocerasNautiloid092313.jpg|200px]]
|-
| 390 Ma
|
'''Order:'''
* [[Bactritida]]
|
* Member of the Nautiloids.
* Direct ancestor of the ammonoids.
|
|
|
|-
| 370 Ma
|
'''Subclass:'''
* [[Ammonoidea]]
|
* Direct descendants of Bactirida.
|
|
| [[File:Ammonite Asteroceras.jpg|200px]]
|}
 
==Cephalopods==
{{further|cephalopods}}
{|class="wikitable" style="margin:auto; width:100%;"
|-
! colspan="7" style="text-align:center;" |The ''[[Cephalopod]]'' Evolutionary Series
|-
! Appearance
! Taxa
! Relationships
! Status
! Description
!Location
! Image
|-
| 296 Ma
|
'''Genus'''
* ''[[Pohlsepia]]''
|
|
|Described as earliest octopod, though later study shows that may not even be a mollusk.<ref>{{Cite journal |last1=Whalen |first1=Christopher D. |last2=Landman |first2=Neil H. |date=2022-03-08 |title=Fossil coleoid cephalopod from the Mississippian Bear Gulch Lagerstätte sheds light on early vampyropod evolution |journal=Nature Communications |language=en |volume=13 |issue=1 |pages=1107 |doi=10.1038/s41467-022-28333-5 |pmid=35260548 |pmc=8904582 |bibcode=2022NatCo..13.1107W |issn=2041-1723}}</ref>
|
|
|-
| 164 Ma
|
'''Genus:'''
* ''[[Proteroctopus]]''
|
|
| A primitive [[octopod]].
|{{Flag|France}}
|<!-- [[WP:NFCC]] violation: [[File:Proteroctopus ribeti.jpg|200px]] -->
|-
| 164.7 Ma
|
'''Genus:'''
* ''[[Vampyronassa]]''
|
|
|
An early member of the [[Vampyromorphida]].
|
{{Flag|France}}
|
[[File:Vampylarge.JPG|150px|center]]
|-
| 94.3 Ma
|
'''Genus:'''
* ''[[Palaeoctopus]]''
|
|
| A primitive [[octopod]].
|{{Flag|Mexico}}
|<!-- [[WP:NFCC]] violation: [[File:Palaeoctopus newboldi.jpg|200px]] -->
|}
 
==Evolution of insects==
{{further|evolution of insects}}
{|class="wikitable" style="margin:auto; width:100%;"
|-
|+The ''[[Insect]]'' evolutionary series
|-
! Appearance
! Taxa
! Relationships
! Status
! Description
!Location
! Image
|-
|
411 Ma
|
'''Genus:'''
* ''[[Rhyniognatha]]''
|
|
|
Described as the world's oldest known insect, though later study shows that may be a [[Myriapoda|myriapod]].<ref>{{Cite journal |last1=Haug |first1=Carolin |last2=Haug |first2=Joachim T. |date=2017-05-30 |title=The presumed oldest flying insect: more likely a myriapod? |journal=PeerJ |volume=5 |pages=e3402 |doi=10.7717/peerj.3402 |issn=2167-8359 |pmc=5452959 |pmid=28584727}}</ref>
|
{{Flag|UK}}
|
|-
|
411 Ma
|
'''Genus:'''
* ''[[Rhyniella]]''
|
|
|
Early [[springtail]].
|
{{Flag|UK}}
|
|-
|
300 Ma
|
'''Genus:'''
* ''[[Archimylacris]]''
|
|
|
Early [[cockroach]]-like insect.
|
|
|-
|
316.5 Ma
|
'''Genus:'''
* ''[[Aphthoroblattina]]''
|
|
|
Early [[cockroach]]-like insect.
|
|
|-
|
140 Ma
|
'''Genus:'''
* ''[[Archaeolepis]]''
|
|
|
The earliest known [[Lepidopteran]].
|
|
|-
|
100 Ma
|
'''Genus:'''
[[Manipulator (insect)]]
|
|
|
Possible common ancestor between Cockroaches and Praying Mantises.
|
|
|-
|
80 Ma
|
'''Genus:'''
* ''[[Sphecomyrma]]''
|
|
|
The earliest known species of [[ant]].
|
{{Flag|USA}}
|
[[File:Sphecomyrma freyi AMNH-NJ943B.jpg|thumb|150px|center]]
|-
| 56–34 Ma
|
'''Genus:'''
* ''[[Eophyllium]]''
|
|
|
First [[leaf insect]] from the fossil record.
|
{{Flag|Germany}}
|
|-
|
52 Ma
|
'''Genus:'''
* ''[[Protoclaviger]]''
|
|
|
Transitional fossil [[myrmecophile]] (social parasite of ant colonies) of the [[rove beetle]] subfamily [[Pselaphinae]].
|
{{Flag|India}}
|
|}
 
==Evolution of spiders==
{{further|evolution of spiders}}
{| class="wikitable" style="margin:auto; width:100%;"
|-
! colspan="6" style="text-align:center;"|The ''[[Spider]]'' Evolutionary Series
|-
! Appearance
! Taxa
! Relationships
! Status
! Description
! Image
|-
| 390 Ma
|
'''Genus:'''
* ''[[Attercopus]]''
|
|
|Previously thought to be the world's oldest spider.
|
|-
| 165 Ma
|
'''Genus'''
* ''[[Eoplectreurys]]''
|
|
|The oldest known [[haplogyne]] spider.
|
|}
 
==Invertebrates to fish==
{{Expand list|date=August 2008}}
{|class="wikitable" style="margin:auto; width:100%;"
|-
! colspan="6" style="text-align:center;"|'''The ''[[Invertebrates]]'' → ''[[Fish]]'' Evolutionary Series'''
|-
! Appearance
! Taxa
! Relationships
! Status
! Description
! Image
|-
| 523 Ma
|
'''Genus:'''
* ''[[Pikaia]]''
|
|
|Possible stem-[[chordate]].<ref>{{Cite journal |last1=MALLATT |first1=JON |last2=HOLLAND |first2=NICHOLAS |date=2013-04-18 |title=Pikaia gracilens Walcott: Stem Chordate, or Already Specialized in the Cambrian? |url=https://onlinelibrary.wiley.com/doi/full/10.1002/jez.b.22500 |journal=Journal of Experimental Zoology Part B: Molecular and Developmental Evolution |volume=320 |issue=4 |pages=247–271 |doi=10.1002/jez.b.22500 |pmid=23606659 |issn=1552-5007}}</ref>
 
'''Vertebrate characters'''
* Very primitive proto-[[notochord]].
|
[[File:Pikaia Smithsonian.JPG|200px]]
|-
| 504 Ma
|
'''Class:'''
* [[Conodont]]
| Had fin rays, chevron-shaped [[muscles]] and a notochord.
|
|
| [[File:Conodonts.jpg|200px]]
|-
| 530 Ma
|
'''Genus:'''
* ''[[Haikouichthys]]''
|
|
|Appears to have a [[cranium]], thus being a [[Craniata|craniate]].<ref name=Shu2003>{{citation
| title = Head and backbone of the Early Cambrian vertebrate ''Haikouichthys''
| journal = Nature | first11 = H. -Q. | first1 = D. G.
| last11 = Liu | last1 = Shu | first2 = S. C. | first10 = Y. | last2 = Morris | first3 = J. | last3 = Han | first4 = Z. F. | last4 = Zhang
| last10 = Li | first5 = K. | last5 = Yasui | first6 = P. | last6 = Janvier | first7 = L. | last7 = Chen | first8 = X. L. | last8 = Zhang | first9 = J. N. | last9 = Liu
| volume = 421
| issue = 6922
| doi = 10.1038/nature01264
| bibcode = 2003Natur.421..526S
| pmid = 12556891
| url=https://www.researchgate.net/publication/10926399
| pages = 526–529
| date =2003
| s2cid = 4401274 }}</ref>
| [[File:Haikouichthys NT.jpg|200px]]
|-
| 480 to 470 Ma
|
'''Genus:'''
* ''[[Arandaspis]]''
|
|[[Agnatha|Jawless fish]]
|A well armoured [[Agnatha|jawless fish]], resembling a large tadpole in life
| [[File:Arandaspis prionotolepis fossil.jpg|200px]]
|-
| 422–412 Ma
|
'''Genus:'''
* ''[[Birkenia]]''
|
|An [[Anaspida|anaspid]], ancestral to the [[gnathostomes|jawed vertebrates]],<ref name="isbn978-0-415-23370-5">{{cite book |author=Ahlberg, Per Erik |title=Major Events in Early Vertebrate Evolution: Palaeontology, Phylogeny, Genetics, and Development |publisher=Taylor & Francis |___location=Washington, DC |year=2001 |isbn=978-0-415-23370-5 |url=https://books.google.com/books?id=zeyRZNZl-74C&q=Anaspida+%22stem+gnathostomes%22&pg=PA188 |page=188}}</ref>
|An unarmored, scaly [[Agnatha|jawless fish]]
| [[File:Birkenia elegans.jpg|200px]]
|-
| 419 Ma
|
'''Genus:'''
* ''[[Guiyu (fish)|Guiyu]]''
|
|Oldest known [[Osteichthyes|bony fish]]<ref>{{cite journal |last1=Zhu |first1=M. |last2=Zhao |first2=W. |last3=Jia |first3=L. |last4=Lu |first4=J. |last5=Qiao |first5=T. |last6=Qu |first6=Q. |year=2009 |title=The oldest articulated osteichthyan reveals mosaic gnathostome characters |journal=[[Nature (journal)|Nature]] |volume=458 |issue=7237 |pages=469–474 |bibcode=2009Natur.458..469Z |doi=10.1038/nature07855 |pmid=19325627|s2cid=669711 }}</ref>
|
| [[File:Guiyu BW.jpg|200px]]
|}
 
==[[Chondrichthyes]]==
{{Expand list|date=July 2010}}
{|class="wikitable" style="margin:auto; width:100%;"
|-
! colspan="6" style="text-align:center;"|The ''[[Chondrichthyes]]'' Evolutionary Series
|-
! Appearance
! Taxa
! Relationships
! Status
! Description
! Image
|-
| 370 Ma
|
'''Genus:'''
* ''[[Cladoselache]]''
|
|
|An early primitive shark-like [[Holocephali|holocephalian]].<ref>{{Cite journal |last1=Frey |first1=Linda |last2=Coates |first2=Michael I. |last3=Tietjen |first3=Kristen |last4=Rücklin |first4=Martin |last5=Klug |first5=Christian |date=2020-11-17 |title=A symmoriiform from the Late Devonian of Morocco demonstrates a derived jaw function in ancient chondrichthyans |journal=Communications Biology |language=en |volume=3 |issue=1 |page=681 |doi=10.1038/s42003-020-01394-2 |pmid=33203942 |pmc=7672094 |issn=2399-3642}}</ref><ref>{{Cite journal |last1=Coates |first1=Michael I. |last2=Gess |first2=Robert W. |last3=Finarelli |first3=John A. |last4=Criswell |first4=Katharine E. |last5=Tietjen |first5=Kristen |date=2017 |title=A symmoriiform chondrichthyan braincase and the origin of chimaeroid fishes |url=https://www.nature.com/articles/nature20806 |journal=Nature |language=en |volume=541 |issue=7636 |pages=208–211 |doi=10.1038/nature20806 |pmid=28052054 |bibcode=2017Natur.541..208C |s2cid=4455946 |issn=1476-4687}}</ref>
|[[File:Cladoselache.png|frameless]]
|-
| 70–65 Ma
|
'''Genus:'''
* ''[[Dalpiazia]]''
|
|
|An early [[sawfish]]-like [[Rajiformes|skate]] relative
|
|-
| 99–65 Ma
|
'''Genus:'''
* ''[[Cyclobatis]]''
|
|
| An early [[stingray]]-like [[Skate (fish)|skate]]
|[[File:Cyclobatis major 1.JPG|200px]]
|}
 
==Bony fish==
{{further|bony fish}}
{{Expand list|date=May 2010}}
{|class="wikitable" style="margin:auto; width:100%;"
|-
! colspan="6" style="text-align:center;"|'''The ''[[bony fish]]'' evolutionary series'''
|-
! Appearance
! Taxa
! Relationships
! Status
! Description
! Image
|-
| 420 Ma
|
'''Genus:'''
* ''[[Andreolepis]]''
|
|
|
The earliest-known [[Actinopterygii]]an.
|
|-
| 48–37 Ma
|
'''Genus:'''
* ''[[Amphistium]]''
|
|
|An early relative of the [[flatfish]]es, one eye had already migrated towards the body midline.
|[[File:Amphistium.JPG|200px]]
|-
| 48–37 Ma
|
'''Genus:'''
* ''[[Eobothus]]''
|
|
|The earliest known true [[flatfish]]
|
|-
| 183.7–125.0 Ma
|
'''Genus:'''
* ''[[Leptolepis]]''
|
|
|One of the first [[teleost]]s.
|[[File:Leptolepis dubia cm4694.jpg|200px]]
|-
| 13 Ma
|
'''Genus:'''
* ''[[Hippocampus sarmaticus]]''
|
|
|One of the oldest known [[seahorse]]s.
|[[File:Tunjice Hills Hippocampus.jpg|200px]]
|-
| 13 Ma
|
'''Genus:'''
* ''[[Hippocampus slovenicus]]''
|
|
|One of the oldest known [[seahorse]]s.
|[[File:Hippocampus slovenicus.jpg|200px]]
|-
| 83–70 Ma
|
'''Genus:'''
* ''[[Nardovelifer]]''
|
|
|The oldest known [[Lampridiformes|lamprid]] fish
|[[File:Nardovelifer altipinnis.jpg|150px]]
|-
| 56–34 Ma
|
'''Genus:'''
* ''[[Eomola]]''
|
|
|A primitive [[Molidae|sunfish]]
|
|-
| 58–55 Ma
|
'''Genus:'''
* ''[[Corydoras revelatus]]''
|
|
|The oldest known member of the [[catfish]] family [[Callichthyidae]].
|[[File:Corydoras revelatus.JPG|200px]]
|-
| 56–34 Ma
|
'''Genus:'''
* ''[[Ruffoichthys]]''
|
|
|A primitive [[rabbitfish]].
|
|-
| 48–37 Ma
|
'''Genus:'''
* ''[[Palaeoperca]]''
|
|
|A primitive [[perch]]
|[[File:Palaeoperca proxima.jpg|200px]]
|-
| 58–55 Ma
|
'''Genus:'''
* ''[[Trachicaranx]]''
|
|
|A primitive [[pomfret]]
|[[File:Trachicaranx tersus.jpg|200px]]
|-
| 48–40 Ma
|
'''Genus:'''
* ''[[Histionotophorus]]''
|
|
|An early [[handfish]]
|
|-
| 48–40 Ma
|
'''Genus:'''
* ''[[Eolactoria]]''
|
|
|The oldest known [[ostraciid]] [[boxfish]]
|[[File:Eolactoria sorbinii.jpg|200px]]
|-
| 48–40 Ma
|
'''Genus:'''
* ''[[Proaracana]]''
|
|
|The oldest known aracanid [[boxfish]]
|[[File:Proaracana dubia.jpg|200px]]
|-
| 48–40 Ma
|
'''Genus:'''
* ''[[Gazolaichthys]]''
|
|
|A basal [[surgeonfish]]
|
|-
| 48–40 Ma
|
'''Genus:'''
* ''[[Psettopsis]]''
|
|
|A primitive monodactylid [[moonyfish]]
|[[File:Psettopsis subarcuatus.jpg|200px]]
|-
| 48–40 Ma
|
'''Genus:'''
* ''[[Pasaichthys]]''
|
|
|A primitive monodactylid [[moonyfish]]
|[[File:Pasaichthys pleuronectiformis.jpg|200px]]
|-
| 48–40 Ma
|
'''Genus:'''
* ''[[Eozanclus]]''
|
|
|A short-snouted ancestor of the modern [[Moorish Idol]].
|
|-
| 83–65 Ma
|
'''Genus:'''
* ''[[Cretatriacanthus]]''
|
|
|A primitive member of the [[Tetraodontidae]]
|
|-
| 83–65 Ma
|
'''Genus:'''
* ''[[Nardoichthys]]''
|
|
|A primitive [[Perciforme]]
|
|-
| 58–55 Ma
|
'''Genus:'''
* ''[[Protozeus]]''
|
|
|A primitive member of the [[Zeidae]]
|
|-
| 58–55 Ma
|
'''Genus:'''
* ''[[Archaeozeus]]''
|
|
|A primitive member of the [[Zeidae]]
|
|-
| ??? Ma
|
'''Genus:'''
* ''[[Cooyoo]]''
|
|
|A primitive member of the [[Ichthyodectidae]]
|[[File:Cooyoo australis.jpg|200px]]
|-
| 65 Ma
|
'''Genus:'''
* ''[[Protriacanthus]]''
|
|
|A primitive [[tetraodontid]]
|
|}
 
==Fish to tetrapods==
{|class="wikitable" style="margin:auto; width:100%;"
|-
! colspan="6" style="text-align:center;"|'''The ''[[Fish]]'' → ''[[Tetrapods]]'' Evolutionary Series'''
|-
! Appearance
! Taxa
! Relationships
! Status
! Description
! Image
|-
| 416–359 Ma
|
'''Genus:'''
* ''[[Osteolepis]]''
| An early member of the [[Tetrapodomorpha]], the piscine line leading to tetrapods, ''[[Osteolepis]]'' is generalised enough to give a fair approximation of the common ancestor of tetrapods and [[lungfish]].<ref name=AhlbergJohansen>{{cite journal |last=Ahlberg |first=P. E. |author2=Johanson, Z. |year=1998 |title=Osteolepiforms and the ancestry of tetrapods |journal=Nature |volume=395 |pages=792–794 |doi=10.1038/27421 |issue=6704 |url=http://www.biology.ualberta.ca/courses.hp/biol606/papers/Ahlberg+1998.pdf |bibcode=1998Natur.395..792A |s2cid=4430783 |access-date=13 March 2011 |archive-url=https://web.archive.org/web/20141124103604/http://www.biology.ualberta.ca/courses.hp/biol606/papers/Ahlberg+1998.pdf |archive-date=24 November 2014 |url-status=dead}}</ref>
| Fish
| A small to medium-sized [[sarcopterygian]] fish with internal nostrils and pectoral fins stiffened by bony components broadly [[Homology (biology)|homologous]] to the [[humerus]] and [[radius (bone)|radius]]/[[ulna]] found in tetrapods.<ref name=AhlbergJohansen/>
| [[File:Osteolepis macrolepidotus.jpg|150px]]
|-
| 385 Ma
|
'''Genus:'''
* ''[[Eusthenopteron]]''
| Belonging to the family [[Tristichopteridae]], a [[family (biology)|family]] that form a sister group to ''[[Panderichthys]]'' and the tetrapods.<ref name=AhlbergJohansen />
| Though not on the evolutionary path to tetrapods, ''Eusthenopteron'' is of fairly general build and is very well known, serving as an iconic model organism in tetrapod evolution.<ref name=Cloutier>{{cite book |author=R. Cloutier|chapter=Taxonomic review of ''Eusthenopteron foordi''. |title=Devonian Fishes and Plants of Miguasha, Quebec, Canada |publisher=Dr. Friedrich Pfeil, München |pages=487–502 |year=1996}}</ref>
| A medium-sized, mainly [[pelagic]] fish, ''[[Eusthenopteron]]'' mainly use the pectoral and pelvic fins for navigation, and the tail for propulsion.<ref name=Cloutier /> The fin was of diphycercal, foreshadowing the straightening of the spine and the evolution of a contiguous fin in fish like ''[[Panderichthys]]''
| [[File:Eusthenopteron foordi 1.JPG|150px]]
|-
| 380 Ma
|
'''Genus:'''
* ''[[Panderichthys]]''
| Very close to the origin of tetrapods, a "fishapod" [[elpistostegalia]]n.<ref name=AhlbergJohansen/>
| Fish
| A large, predatory shallow water fish. As common in shallow water fish, the pectoral and pelvic fins were flexible and paddle-like for propulsion.<ref>Nature: [http://www.nature.com/nature/journal/v438/n7071/edsumm/e051222-13.html The pelvic fin and girdle of ''Panderichthys'' and the origin of tetrapod locomotion]</ref> The dorsal and anal fins are lost, the tail fin contiguous.<ref>{{cite journal |last1=Carroll |first1=R. |author-link=Robert L. Carroll |year=1995 |title=Between fish and amphibians |journal=Nature |volume=373 |issue=6513|pages=389–390 |bibcode=1995Natur.373..389C |doi=10.1038/373389a0 |s2cid=5412926 }}</ref> The [[Spiracle (vertebrates)|spiracle]]s were short and wide, indication large amount of oxygen were taken up by the lungs rather than through the gills.<ref>{{cite journal |last1=Brazeau |first1=M.D. |last2=Ahlberg |first2=P.E. |year=2006 |title=Tetrapod-like middle ear architecture in a Devonian fish |journal=[[Nature (journal)|Nature]] |volume=439 |issue=7074|pages=318–321 |pmid=16421569 |doi=10.1038/nature04196|bibcode=2006Natur.439..318B|s2cid=4301561 }}</ref>
| [[File:Panderichthys BW.jpg|150px]]
|-
| 375 Ma
|
'''Genus:'''
* ''[[Tiktaalik]]''
| A "[[fishapod]]" more tetrapod-like than ''[[Panderichthys]]''.<ref name=AhlbergJohansen/>
| A fish, transitional between fish and the early, fish-like [[labyrinthodont]]s.<ref>John Noble Wilford, ''The New York Times'', [https://www.nytimes.com/2006/04/05/science/05cnd-fossil.html?hp&ex=1144296000&en=fe3427d67e965e46&ei=5094&partner=homepage ''Scientists Call Fish Fossil the Missing Link''], 5 April 2006.</ref><ref name="Shubin 2008">{{cite book|last=Shubin|first=Neil|title=Your Inner Fish|publisher=Pantheon|year=2008|isbn=978-0-375-42447-2|url-access=registration|url=https://archive.org/details/yourinnerfishjou00shub_0}}</ref>
| "Fish" with stout, fleshy pectoral fins with a joint between the innermost and the two next bony elements, corresponding to the elbow in higher tetrapods. The [[cleithrum]] bone was free of the skull, functioning as anchoring for the pectoral fins, and at the same time allowing for movement of the neck.<ref name="Shubin 2008"/><ref name="newscientist.com">{{cite web | url = https://www.newscientist.com/channel/life/mg19125681.500-meet-your-ancestor--the-fish-that-crawled.html;jsessionid=NDHPCECNAGNA| title = Meet Your ancestor, the Fish that crawled | publisher = New Scientist Magazine | access-date = 2007-02-07}}</ref>
| [[File:Tiktaalik belgium.JPG|150px]]
|-
| 368 Ma
|
'''Genus:'''
* ''[[Elginerpeton]]''
| Analysis of the cranial material shows it was more advanced than ''[[Tiktaalik]]'', and together with ''[[Obruchevichthys]]'' form a sister group to the higher tetrapods.<ref name=Elginerpeton>{{cite journal|last=Ahlberg|first=Per E.|title=Elginerpeton pancheni and the earliest tetrapod clade|journal=Nature|year=1995|volume=373|issue=6513|pages=420–425|doi=10.1038/373420a0|bibcode = 1995Natur.373..420A |s2cid=4344655}}</ref>
| A fairly fragmentary find, ''Elginerpeton'' straddles the fish/tetrapod divide with a mosaic of features resembling ''[[Panderichthys]]'', ''[[Ichthyostega]]'' and ''[[Hynerpeton]]''.<ref name=Elginerpeton/> Probably one of the "[[fishapod]]s".<ref>''[http://www.devoniantimes.org/Order/re-elginerpeton.html Elginerpeton pacheni]'' at [http://www.devoniantimes.org/index.html Devonian Times] {{webarchive |url=https://web.archive.org/web/20050204224430/http://devoniantimes.org/index.html |date=4 February 2005 }}</ref>
| Though fragmentary, the find includes a shoulder blade (Cleitrum bone) as well as elements of the limbs, which shows it had comparable limbs ''[[Ichthyostega]]'' and ''[[Hynerpeton]]'', indicating feet rather than fins.
| [[File:Elginerpeton BW.jpg|150px]]
|-
| 365 Ma
|
'''Genus:'''
* ''[[Ventastega]]''
| Known only from fragmentary remains, mostly a lower jaw, ''Ventastega'' is morphologically midway between ''[[Tiktaalik]]'' and ''[[Acanthostega]]''/''[[Ichthyostega]]''.<ref name=Ventastega>{{cite journal|first=Per. E. |last=Ahlberg |author2=Jennifer A. Clack |author3=Ervins Luksevics |author4=Henning Blom |author5=Ivars Zupins |title=''Ventastega curonica'' and the origin of tetrapod morphology|journal=[[Nature (journal)|Nature]] |volume=453|issue=7199|date=26 June 2008|pages=1199–1204|doi=10.1038/nature06991|pmid= 18580942|bibcode=2008Natur.453.1199A|s2cid=4344417 |url=http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-105437 |author2-link=Jennifer A. Clack }} [https://uppsala.academia.edu/PerAhlberg/Papers/412448/Ventastega_curonica_and_the_origin_of_tetrapod_morphology article]</ref>
| Possibly oldest animal to have feet rather than fins.<ref name=Ventastega/>
| A large, dorso-ventrally flattened predatory fish with a well armoured [[labyrinthodont]]-like skull. While the fins themselves has not been found, the [[shoulder girdle]] is essentially similar to that of ''Acanthostega'', indicating it too had feet rather than fins.<ref name=Ventastega/>
| [[File:Ventastega BW.jpg|150px]]
|-
| 365 Ma
|
'''Genus:'''
* ''[[Acanthostega]]''
|
| Together with ''[[Ichthyostega]]'' the sole early [[labyrinthodont]] known from fairly complete skeletons. It is the oldest animal known to have feet rather than fins, thus making it a true [[tetrapod]] and the oldest known unquestionable [[ichthyostegalia]]n.<ref name="scientificamerican">{{cite journal |author=Clack, J. |author-link=Jennifer A. Clack |journal=Scientific American |volume=293 |issue=6 |pages=100–7 |url=http://sciam.com/print_version.cfm?articleID=000DC8B8-EA15-137C-AA1583414B7F0000 |title=Getting a leg up on land |date=2005-11-21 |archive-url=https://web.archive.org/web/20061104124433/http://www.sciam.com/print_version.cfm?articleID=000DC8B8-EA15-137C-AA1583414B7F0000 |archive-date=2006-11-04|bibcode=2005SciAm.293f.100C |doi=10.1038/scientificamerican1205-100 |pmid=16323697 }}</ref>
| First known animal with toes rather than fins. The feet were broad and paddle-like, adapted for movement in water.<ref>"[http://www.devoniantimes.org/Order/re-acanthostega.html Acanthostega gunneri]," ''Devonian Times''. {{webarchive |url=https://web.archive.org/web/20041224201223/http://www.devoniantimes.org/Order/re-acanthostega.html |date=24 December 2004 }}</ref> It retained functional gills in adulthood, behind a fleshy [[operculum (animal)|operculum]].
| [[File:Acanthostega.JPG|150px]]
|-
| 365 Ma
|
'''Genus:'''
* ''[[Ichthyostega]]''
| Fairly closely related to ''[[Acanthostega]]''. It possibly represents an early (and ultimately unsuccessful) line adapted to moving on land by [[Geometer moth|inchworm]]-like movements.
| Together with ''Acanthostega'' the sole early [[labyrinthodont]] known from fairly complete skeletons.
| Early labyrinthodont with [[Polydactyly in early tetrapods|polydactylous]], paddle-like feet and reinforced vertebrae and neural spines. It probably spent time on land, yet retained gills and a tail with [[fin ray]]es.
| [[File:Ichthyostega skull.jpg|150px]]
|-
| 365 Ma
|
'''Genus:'''
* ''[[Tulerpeton]]''
|
| An advanced [[ichthyostegalia]]n, it straddled the divide between the fish-like [[Devonian]] forms and the more advanced [[Carboniferous]] amphibians. It has been suggested it is an early [[Reptiliomorpha|reptil-like amphibian]].<ref>{{cite journal|last=Lebedev|first=O.A.|title=The first find of a Devonian tetrapod vertebrate in the USSR|journal=Doklady Akademii Nauk SSSR|year=1984|volume=278|series=Palaeontology|pages=1470–1473|language=ru}}</ref>
| A large animal with paddle-like six-toed feet. However, it did not have gills in adulthood, and is thus the oldest [[labyrinthodont]] known to depend entirely on breathing with its lungs.<ref>{{cite journal |last1=Gordon |first1=M.S. |last2=Long |first2=J.A. |year=2004 |title=The Greatest Step in Vertebrate History: A Paleobiological Review of the Fish-Tetrapod Transition |url=http://usf.usfca.edu/fac_staff/dever/tetrapod_review.pdf |journal=Physiological and Biochemical Zoology |volume=77 |issue=5|pages=700–719 |doi=10.1086/425183 |pmid=15547790|s2cid=1260442 }}</ref>
| [[File:Tulerpeton12DB.jpg|150px]]
|-
| 360 Ma
|
'''Genus:'''
* ''[[Hynerpeton]]''
| While known only from fragmentary remains, it is more advanced than ''[[Ichthyostega]]''.
| Early [[labyrinthodont]] amphibian
| A large, basically [[salamander]]-like creature. The [[shoulder girdle]] was powerful, indicating it was a competent walker.<ref>{{cite book |title=Your Inner Fish: A Journey into the 3.5-Billion-Year History of the Human Body |last=Shubin |first=Neil |author-link=Neil Shubin |year=2009 |publisher=Vintage |___location=New York |isbn=978-0-307-27745-9 |page=13}}</ref>
| [[File:Hynerpeton BW.jpg|150px]]
|-
| 359–345 Ma
|
'''Genus:'''
* ''[[Pederpes]]''
| Hailing from the fossil-poor [[Romer's Gap]], ''Pederpes'' may be ancestral to the higher [[labyrinthodont]]s.
| Intermediate between the earlier [[Ichthyostegalia]]n and the later, more advanced labyrinthodonts.
| Despite an extra toe on the forelimbs, ''Pederpes'' had limbs that terminated in feet adapted primarily for walking rather than paddles for combined swimming and walking like the earlier groups.<ref name=CJA02>{{cite journal |last=Clack |first=J. A. |year=2002 |title=An early tetrapod from 'Romer's Gap' |journal=Nature | volume=418 |pages=72–76 | doi=10.1038/nature00824 |pmid=12097908 |issue=6893|bibcode=2002Natur.418...72C |s2cid=741732 }}</ref>
| [[File:Pederpes22small.jpg|150px]]
|-
| 295 Ma
|
'''Genus:'''
* ''[[Eryops]]''
| The [[Temnospondyli]] are derived paleozoic amphibians, possibly ancestral to [[lissamphibia|modern amphibians]]
| A "classical" [[Temnospondyli|temnospondyl]], an advanced [[labyrinthodont]] group.
| One of the best known [[labyrinthodont]]s, ''Eryops'' combines the large, flat skull and short limbs typical of the group.
|[[File:Eryops1DB.jpg|alt=|150x150px]]
|}
 
{|class="wikitable" style="margin:auto; width:100%;"
|-
! colspan="6" style="text-align:center;"|'''The ''[[Labyrinthodontia]]'' → ''[[Lissamphibia]]'' Evolutionary Series'''
|-
! Appearance
! Taxa
! Relationships
! Status
! Description
! Image
|-
| 290 Ma
|
'''Genus:'''
* ''[[Gerobatrachus]]''
|Colloquially referred to as a "frogamander" due to this taxon being both chronologically and morphologically basal to both [[anura (frog)|anura]]ns and [[Caudata|salamanders]]
|One of the first transitional fossils towards modern amphibians ([[Lissamphibia]]).<ref name=Anderson>{{cite journal |last1=Anderson |first1=J. S. |last2=Reisz |first2=R. R. |last3=Scott |first3=D. |last4=Fröbisch |first4=N. B. |last5=Sumida |first5=S. S. |year=2008 |title=A stem batrachian from the Early Permian of Texas and the origin of frogs and salamanders |journal=[[Nature (journal)|Nature]] |volume=453 |issue=7194 |pages=515–518 |doi=10.1038/nature06865 |pmid=18497824 |bibcode=2008Natur.453..515A|s2cid=205212809 }}</ref>
|'''Primitive traits'''
* Backbone with intermediate characteristics
* Retains a fully developed tail
'''Derived traits'''
* Bears a large space for a tympanic ear
* Ankle bones are fused together like in salamanders
* Lightly built wide skull as in frogs<ref name=Anderson/>
|
[[File:Gerobatrachus NT.jpg|150px]]
|-
| 250 Ma
|
'''Genus:'''
* ''[[Triadobatrachus]]''
|Intermediate between generalized amphibians and derived frogs
|Early "almost frog" transitional amphibian
|'''Primitive traits'''
* Possessed short limbs and therefore was unable to hop, unlike all extant anurans
* Retains fourteen vertebra unlike modern frogs who have four to nine vertebra
* Tibia and fibula are not fused into a tibiofibula
'''Derived traits'''
* Skull resembles that of modern [[anura (frog)|anura]]n skull with a latticework of thin bones in skull
|
[[File:Triadobatrachus BW.jpg|200px]]
|-
| 190 Ma
|
'''Genus:'''
* ''[[Prosalirus]]''
|Another transitional form which could be properly classified as a frog
|An intermediate form which may replace [[Triadobatrachus]] as the "ultimate" ancestor of anurans
|'''Primitive traits'''
* Still possess relatively short limbs
'''Derived traits'''
* Tail is greatly reduced
* Does not have greatly enlarged legs, but shows some adaptations for hopping, such as a three-pronged pelvis
|[[File:Prosalirus BW.jpg|200px]]
|-
| 213–188 Ma
|
'''Genus:'''
* ''[[Vieraella]]''
|A derived fossil frog completing the series of transitional fossils between early amphibians and modern anurans
|The oldest "true" frog<ref>Estes, R., and O. A. Reig. (1973): "The early fossil record of frogs: a review of the evidence." Pp. 11–63 In J. L. Vial (Ed.), ''Evolutionary Biology of the Anurans: Contemporary Research on Major Problems''. University of Missouri Press, Columbia.</ref>
|'''Primitive traits'''
* Retains ten presacral vertebra
'''Derived traits'''
* Hind legs are adapted for hopping
|
[[File:Vieraella NT.jpg|150px]]
|-
| 210 Ma
|
'''Genus:'''
* ''[[Eocaecilia]]''
|Intermediate between basal amphibians and [[caecilian]]s
|An early [[caecilian]]
|'''Primitive traits'''
* Bears three-toed vestigial limbs
* The size of the orbits indicates well developed eyes and suggest a non-subterranean lifestyle
'''Derived traits'''
* The body has been adapted to a sort of serpentine shape
|
[[File:Eocaecilia BW.jpg|200px]]
|}
 
==Amphibians to [[amniotes]] ==
{|class="wikitable" style="margin:auto; width:100%;"
|-
! colspan="6" style="text-align:center;"|'''The ''[[Amphibians]]'' → ''[[Reptiles]]'' Evolutionary Series'''
|-
! Appearance
! Taxa
! Relationships
! Status
! Description
! Image
|-
| 326–318 Ma
|
'''Genus:'''
* ''[[Proterogyrinus]]''
| One of the early [[Reptiliomorpha|reptile-like]] amphibians
| Amphibian
| A large, somewhat lizard-like [[labyrinthodont]] with a deep skull, laterally placed eyes and five digits to each foot.
| [[File:Proterogyrinus NT.jpg|150px]]
|-
| ??? Ma
|
'''Genus:'''
* ''[[Limnoscelis]]''
| The order [[Diadectomorpha]] is the sister group of the [[amniote]]s.
| The ''Limnoscelis'' was originally described as a "[[cotylosaur]]" (early reptiles) together with the other [[diadectomorpha]]ns. Today the large-bodied diadectomorphs are thought to have had a larval stage, falling close to, but just outside the amphibian/reptile divide.
| A large, predatory reptile-like amphibian. The limbs are extremely heavily built, indicating it fed on slow moving prey.
| [[File:Limnoscelis(Cast)-RedpathMuseumMontreal-June6-08.png|150px]]
|-
| ??? Ma
|
'''Genus:'''
* ''[[Tseajaia]]''
| Uncertain phylogeny, possibly a [[Seymouriamorpha|Seymouriamorph]] or [[Diadectomorpha|Diadectomorph]]<ref>{{cite journal | author = Moss J.L. | year = 1972 | title = The Morphology and phylogenetic relationship of the Lower Permian tetrapod ''Tseajaia campi'' Vaughn (Amphibia: Seymouriamorpha) | journal = University of California Publications in Geological Sciences | volume = 98 | pages = 1–72 }}</ref><ref>{{cite journal | last1 = Berman | first1 = D.S. | last2 = Sumida | first2 = S.S. | last3 = Lombard | first3 = R.E. | year = 1992 | title = Reinterpretation of the temporal and occipital regions in Diadectes and the relationship of diadectomorphs | url = https://semanticscholar.org/paper/37fd36fce03d40b7157c6172ff0c238635dee316| journal = [[Journal of Paleontology]] | volume = 66 | issue = 3| pages = 481–499 | doi = 10.1017/S0022336000034028 | s2cid = 73547163 }}</ref>
| Amphibian
| A medium-sized, probably herbivorous animal
|[[File:Tseajaia BW.jpg|150px]]
|-
| 350 Ma
|
'''Genus:'''
* ''[[Westlothiana]]''
| Uncertain phylogenetic position. ''Westlothiana'' may be a small-bodied [[Diadectomorpha|diadectopmorph]], falling just outside the amphibian/reptile divide
| Originally described as the first [[reptile]], it is now considered an advanced [[Reptiliomorpha|reptile-like amphibian]].
| Small, probably insectovorious animal. The body and tail was long, the limbs small, somewhat like a modern [[skink]].
| [[File:Westlothiana BW.jpg|150px]]
|-
| 320–305 Ma
|
'''Genus:'''
* ''[[Solenodonsaurus]]''
| Possibly allied to the [[Diadectomorpha]], or belonging to a sister group to Diadectomorpha and Amniota<ref name=Solenodonsaurus>Gauthier J., Kluge, A.G., & Rowe, T. (1988) "The early evolution of the Amniota." In: M. J. Benton (ed.) ''The Phylogeny and Classification of the Tetrapods, Volume 1: Amphibians, Reptiles, Birds'' (1): pp 103–155. Oxford: Clarendon Press.</ref>
| Likely an amphibian<ref name=Solenodonsaurus/>
| Smallish, likely carnivorous.<ref>''[http://tolweb.org/Solenodonsaurus_janenschi Solenodonsaurus]'' on the [[Tree of Life Web Project|TOL-web]]</ref>
| [[File:Solenodonsaurus1DB.jpg|150px]]
|-
| 340 Ma
|
'''Genus:'''
* ''[[Casineria]]''
| The fragmentary nature of the fossil (it lacks a [[cranium]]) makes an exact phylogenetic position hard to establish.
| Possibly the first animal with an [[amniote]] egg, and thus the first amniote and thus the latest common ancestor to both [[Synapsids]] and [[sauropsids]].
| Small lizard-like animal, the first known [[tetrapod]] to possess [[claws]], indicating it has amniote type skin with [[scute]]s.<ref name=nature>R. L. Paton, T. R. Smithson and J. A. Clack, "An amniote-like skeleton from the Early Carboniferous of Scotland", [http://www.nature.com/nature/journal/v398/n6727/abs/398508a0.html (abstract)], ''Nature'' 398, 508–513 (8 April 1999)</ref>
| [[File:Casineria kiddi tilted.jpg|150px]]
|-
| 315 Ma
|
'''Genus:'''
* ''[[Hylonomus]]''
| One of several small, basal reptile genera
| Reptile
|once thought to be the common ancestor of both [[synapsids]] and sauropsids, Hylonomus is now considered a eureptilan creature nested inside [[sauropsida]].
| [[File:Hylonomus BW.jpg|150px]]
|-
| 312–304 Ma
|
'''Genus:'''
* ''[[Paleothyris]]''
| One of several small, basal reptile genera
| Reptile (most likely a [[Sauropsida|sauropsid]])
| An early [[anapsid]] reptile. In phylogenetic analysis it falls on the [[Sauropsida|sauropsid]] side, it is thus likely a progenitor of the [[diapsid]]s
|[[File:Paleothyris BACKGROUND.JPG|150px]]
|}
 
==Turtles==
{{further|turtle}}
{| class="wikitable" style="margin:auto; width:100%;"
|-
! colspan="6" style="text-align:center;"|'''The ''[[Turtle]]'' Evolutionary Series'''
|-
! Appearance
! Taxa
! Relationships
! Status
! Description
! Image
|-
| 240 Ma
|
'''Genus:'''
* ''[[Pappochelys]]''
|
|
|
Reptile closely related to turtles.
|
[[File:Bild2 Ur-Schildkröte Zeichnung.jpg|200px]]
|-
| 220 Ma
|
'''Genus:'''
* ''[[Odontochelys]]''
|
|
|
The oldest known turtle. It had a plastron (bottom half of the shell) covering its abdomen. The species broadened ribs are also a key quality as a transitional turtle. It also had teeth and a long tail unlike modern turtles, which earlier ancestors likely had.
|
[[File:Odontochelys semitestacea.jpg|200px]]
|-
| 210 Ma
|
'''Genus:'''
* ''[[Proganochelys]]''
|
|
|
This species has the oldest known shell consisting fully of a carapace and a plastron.
|[[File:Proganochelys Quenstedti.jpg|200px]]
|-
| 164 Ma
|
'''Genus:'''
* ''[[Eileanchelys]]''
|
|
|
An evolutionary bridge between early land turtles and [[sea turtles]].
|
|}
 
==From lizards to snakes==
{| class="wikitable" style="margin:auto; width:100%;"
|-
! colspan="6" style="text-align:center;"|'''The ''[[Lizard]]'' → ''[[Snake]]'' Evolutionary Series'''
|-
! Appearance
! Taxa
! Relationships
! Status
! Description
! Image
|-
|120 Ma
|'''Genus:'''
* ''[[Tetrapodophis]]''
|
|
|Originally described as basal snake, but later study shows that may be snake-like [[Dolichosauridae|dolichosaur]].<ref>{{Cite journal |last1=Caldwell |first1=Michael W. |last2=Simões |first2=Tiago R. |last3=Palci |first3=Alessandro |last4=Garberoglio |first4=Fernando F. |last5=Reisz |first5=Robert R. |last6=Lee |first6=Michael S. Y. |last7=Nydam |first7=Randall L. |date=2021-07-03 |title=Tetrapodophis amplectus is not a snake: re-assessment of the osteology, phylogeny and functional morphology of an Early Cretaceous dolichosaurid lizard |url=https://doi.org/10.1080/14772019.2021.1983044 |journal=Journal of Systematic Palaeontology |volume=19 |issue=13 |pages=893–952 |doi=10.1080/14772019.2021.1983044 |s2cid=244414151 |issn=1477-2019}}</ref>
|
|-
|95 Ma
|'''Genus:'''
* ''[[Pachyrhachis|Pachyrachis]]''
|
|
|A basal snake with two hind-limbs containing a hip, knee, and ankle joint.
|
|-
| 92 Ma
|
'''Genus:'''
* ''[[Eupodophis]]''
|
|
|A transitional form between [[Cretaceous]] [[lizard]]s and limbless snakes retaining distinct, if non-functional, legs.<ref name="RedOrbit">{{cite web |url=http://www.redorbit.com/news/science/1335315/fossilized_snake_with_two_legs_found/ |title=Fossilized Snake With Two Legs Found - Science - redOrbit |access-date=2008-04-16 |date=2008-04-10 }}</ref>
|[[File:Eupodophis descouensi Holotype.jpg|250px]]
|-
| 90 Ma
|
'''Genus:'''
* ''[[Najash]]''
|
|
|Najash is a key transitional form for snakes. It had a skull with containing a mosaic of features from earlier lizards like having bonier, firmer portions, and a large mouth, mobile joints, and sharp teeth like derived snakes. Najash also had two small, but fully formed back legs.
|
|}
 
==Lizards==
{{further|Lizard}}
{{Expand list|date=July 2010}}
{|class="wikitable" style="margin:auto; width:100%;"
|-
! colspan="6" style="text-align:center;"|The ''[[Lizard]]'' Evolutionary Series
|-
! Appearance
! Taxa
! Relationships
! Status
! Description
! Image
|-
| 61–58 Ma
|
'''Genus:'''
* ''[[Anqingosaurus]]''
|
|
|The earliest known [[chameleon]].
|
|-
| 92 Ma
|
'''Genus:'''
* ''[[Dallasaurus]]''
|
|
|A basal [[mosasauroid]] from the [[Upper Cretaceous]] of [[North America]].
|
|-
| 71–82 Ma
|
'''Genus:'''
* ''[[Palaeosaniwa]]''
|
|
|One of the earliest [[Varanoidea]].
|
|-
| 99.42 Ma
|
'''Genus:'''
* ''[[Cretaceogekko]]''
|
|
|The oldest known [[gecko]]
|
|}
 
==Pterosaurs==
{{further|pterosaur}}
{| class="wikitable" style="margin:auto; width:100%;"
|-
! colspan="6" style="text-align:center;"|''[[Rhamphorhynchoidea]]'' → ''[[Pterodactyloidea]]'' Evolutionary Series
|-
! Appearance
! Taxa
! Relationships
! Status
! Description
! Image
|-
| 160 Ma
|
'''Genus:'''
* ''[[Darwinopterus]]''
|
|
|Basal to both [[rhamphorhynchoid]]s and [[pterodactyloid]]s
|[[File:Darwinopterus.jpg|150px]]
|}
 
==Archosaurs to dinosaurs==
{{further|evolution of dinosaurs}}
{{Expand list|date=April 2010}}
 
{| class="wikitable" style="margin:auto; width:100%;"
|-
|+The ''[[Archosauria]]'' → ''[[Dinosauria]]'' series
|-
! Appearance
! Taxa
! Relationships
! Status
! Description
! Image
|-
| 259-252 Ma
|
'''Genus:'''
* ''[[Archosaurus]]''
|
|
|The oldest known archosaur, ''Archosaurus'' was one of the largest land reptiles during the [[Late Permian]], about the size of to today's [[Komodo dragon]]s. It looked somewhat [[crocodile]]-like, with sprawling legs, long jaws, powerful neck muscles and a long tail. A distinct proterosuchid trait is the peculiar hook-shaped mouth.
|
[[File:Archosaurus ross1DB.jpg|200px]]
|-
| ??? Ma
|
'''Genus:'''
* ''[[Marasuchus]]''
|
|
|
|[[File:Marasuchus.JPG|200px]]
|-
| ??? Ma
|
'''Genus:'''
* ''[[Asilisaurus]]''
|
|The oldest known animal on the [[dinosaur]]/[[pterosaur]] side of the archosaurian tree (the [[Ornithodira]]), dating to about 245 million years ago.<ref name=Netal10>{{cite journal |last=Nesbitt |first=S.J. |author2=Sidor, C.A. |author3=Irmis, R.B. |author4=Angielczyk, K.D. |author5=Smith, R.M.H. |author6= Tsuji, L.M.A. |year=2010 |title=Ecologically distinct dinosaurian sister group shows early diversification of Ornithodira |journal=Nature |pmid=20203608 |volume=464 |issue=7285 |pages=95–98 |doi=10.1038/nature08718|bibcode = 2010Natur.464...95N |s2cid=4344048 |author2-link=Sidor, C.A }}</ref>
|A small, lightly built animal. It had a fairly long neck (contrary to the short necked relatives of [[crocodile]]s), but ran on all four legs.
|[[File:Asilisaurus.jpg|200px]]
|-
| ??? Ma
|
'''Genus:'''
* ''[[Spondylosoma]]''
|
|Known from a somewhat fragmentary find, ''Spondylosoma'' was possibly an early dinosaur, or near dinosaur.<ref name=ML04>Langer, M.C. (2004). Basal Saurischia. In: Weishampel, D.B., Dodson, P., and Osmólska, H. (eds.). ''The Dinosauria'' (second edition). University of California Press:Berkeley, 25-46. {{ISBN|0-520-24209-2}}</ref> It has however also been classified as a [[rauisuchia]]n.<ref name=PMG00>{{cite journal | last1 = Galton | first1 = P.M. | year = 2000 | title = Are ''Spondylosoma'' and ''Staurikosaurus'' (Santa Maria Formation, Middle-Upper Triassic, Brasil) the oldest saurischian dinosaurs? | journal = Paläontologische Zeitschrift | volume = 74 | issue = 3| pages = 393–423 | doi=10.1007/bf02988109| s2cid = 140188942 }}</ref>
|
|
|-
| 228 Ma
|
'''Genus:'''
* ''[[Eoraptor]]''
|
|A very early representative of the [[sauropod]] stem line or perhaps even the [[Saurischia]] as a whole.<ref>R.N. Martinez et al. A basal dinosaur from the dawn of the dinosaur era in southwestern Pangaea. ''Science'', Vol. 331, 14 January 2011, p. 206.</ref><ref name="NNews_2011">Kaplan M, [http://www.nature.com/news/2011/110113/full/news.2011.17.html "Move over ''Eoraptor''"], ''http://www.nature.com/news'', 13-1-2011.</ref><ref name=Apaldetti2011>{{cite journal | last1 = Apaldetti | first1 = C | last2 = Martinez | first2 = RN | last3 = Alcober | first3 = OA | last4 = Pol | first4 = D | year = 2011 | title = A New Basal Sauropodomorph (Dinosauria: Saurischia) from Quebrada del Barro Formation (Marayes-El Carrizal Basin), Northwestern Argentina | journal = PLOS ONE | volume = 6 | issue = 11| page = e26964 | doi = 10.1371/journal.pone.0107672 | pmid = 25259845 | pmc = 4178034 | doi-access = free }}</ref>
|A small (1 meter, ~ 10&nbsp;kg) bipedal carnivore with numerous sharp teeth. It was a swift [[digigrade]] runner. The forelimbs were half the length of the hindlimbs and the hands had five fingers
|[[File:EoraptorBrussels.jpg|200px]]
|}
 
==Dinosauria==
{{further|dinosaur}}
{{Expand list|date=June 2010}}
{| class="wikitable" style="margin:auto; width:100%;"
|-
|+The ''[[Dinosauria]]'' evolutionary series
|-
! Appearance
! Taxa
! Relationships
! Status
! Description
! Image
|-
| 228 to 216.5 Ma
|
'''Genus:'''
* ''[[Pisanosaurus]]''
|
|
|
The oldest known [[ornithischian]].
|[[File:Pisanosaurus.jpg|200px]]
|-
| 216–200 Ma
|
'''Genus:'''
* ''[[Thecodontosaurus]]''
|
|
|The most primitive well-known representative of the [[sauropodomorph]] dinosaurs.
|[[File:Thecodontosaurus.jpg|200px]]
|-
| 160 Ma
|
'''Genus:'''
* ''[[Huayangosaurus]]''
|
|
|The oldest and most primitive known [[stegosaur]].
|[[File:Huayangosaurus taibaii 20050707 07.jpg|200px]]
|-
| 90 Ma
|
'''Genus:'''
* ''[[Wannanosaurus]]''
|
|
|A basal [[pachycephalosaur]] from the late [[Cretaceous]].
|
|-
| 160 Ma
|
'''Genus:'''
* ''[[Yinlong]]''
|
|
|A genus of basal [[ceratopsian]] dinosaur from the [[Late Jurassic]] Period of central Asia.
|[[File:Yinlong skull.jpg|200px]]
|-
| 160 Ma
|
'''Genus:'''
* ''[[Guanlong]]''
|
|
|A genus of [[proceratosaurid]] [[tyrannosauroid]] dinosaur, one of the earliest known examples of the lineage.
|[[File:Guanlong fossil.jpg|200px]]
|-
| 126 Ma
|
'''Genus:'''
* ''[[Falcarius]]''
|
|
|An early genus of [[therizinosaur]]
|[[File:Falcarius.jpg|200px]]
|-
| 208–194 Ma
|
'''Genus:'''
* ''[[Scelidosaurus]]''
|
|
|One of the most primitive [[thyreophorans]].
|[[File:Scelidosaurus skeleton.png|200px]]
|-
| 95 Ma
|
'''Genus:'''
* ''[[Protohadros]]''
|
|
|A possible ancestor of the [[hadrosauridae|duck-billed dinosaurs]].
|-
| 120 Ma
|
'''Genus:'''
* ''[[Pelecanimimus]]''
|
|
|A primitive (basal) [[ornithomimosaur]].
|
|}
 
==Dinosaurs to birds==
{{Further|Origin of birds}}
{{Further|Evolution of birds}}
{|class="wikitable" style="margin:auto; width:100%;"
|-
! colspan="6" style="text-align:center;"|'''The ''[[Dinosaur]]s'' → ''[[Evolution of birds|Birds]]'' Evolutionary Series'''
|-
! Appearance
! Taxa
! Relationships
! Status
! Description
! Image
|-
|-
| 152–151 Ma
|
'''Genus:'''
* ''[[Juravenator]]''
|
|
|'''Primitive traits'''
* Undifferentiated hind digits displaying no specialties for climbing
* Spine attaches to the back end of the skull rather than the base
* Moderately long, bony tail
'''Derived traits'''
* Basic proto-feathers cover parts of the body for insulation
| [[File:Juravenator starkae.JPG|150px]]
|-
| 164–152 Ma
|
'''Genus:'''
* ''[[Pedopenna]]''
|
|
|The find is represented only by a hind leg, but one that is very bird-like. It belonged to a small [[maniraptora]]n dinosaur with long, pennaceous feathers on its hind legs and (in all likelihood) arms.
|
|-
| 161–151 Ma
|
'''Genus:'''
* ''[[Anchiornis]]''
|Basal [[troodontid]]
|Although once classified as a bird, ''Anchiornis'' is now considered a basal [[Troodontidae|troodontid]] which bears pennaceous, symmetrical feathers on all four limbs.
|'''Primitive traits'''
* Wings symmetrical and rounded, probably not used for flight but instead insulation, mating displays, and gliding
* Long legs overall morphology similar to that of other [[troodontids]]
* Spine attaches to the back end of the skull rather than the base
* Moderately long, bony tail
'''Derived traits'''
* Flexible wrists which are more similar to aves than other theropods
* Like birds and unlike troodontids, ''Anchiornis'' had arms nearly the same length as the hind legs
* Bore primary and secondary pennaceous symmetrical wings on both arms, legs, toes, and wrist
| [[File:Anchiornis BW.jpg|150px]]
|-
| 150–145 Ma
|
'''Genus:'''
* ''[[Archaeopteryx]]''
|Known for its mosaic of avian and theropod characteristics [[Archaeopteryx]] is both the first primitive bird in the fossil record and one of the first [[transitional fossils]] discovered.
|Traditionally seen as the first proper bird, though it is not directly ancestral to modern birds.<ref>Padian, K. & Chiappe, L.M. (1997): Bird Origins. In: ''Encyclopedia of Dinosaurs'' (red. Currie, P.J & Padian, K., [[Academic Press]], [[San Diego]], pp 41–96, {{ISBN|978-0-12-226810-6}}</ref> An excellent intermediate form between dinosaurs and birds. Capable of gliding, but lacking [[alula]] and [[Keel (bird)|keel]], it could likely not sustain powered flight.
|'''Primitive traits'''
* Slower dinosaur-like growth rate
* No [[Keel (bird)|keel]]
* Spine attaches to the back end of the skull rather than the base
* Forelimbs have three unfused, clawed fingers, no [[alula]]
* Maxilla and premaxilla bore unserrated teeth
* Moderately long, bony tail
'''Derived traits'''
* Fully developed asymmetrical flight feathers
* Fused [[furcula]] from two joined clavicles
* Backward and elongated pubis similar to maniraptors, but not found in more primitive theropods
| [[File:Archaeopteryx lithographica (Berlin specimen).jpg|150px]]
|-
| 120 Ma
|
'''Genus:'''
* ''[[Confuciusornis]]''
|Found in the famous [[Liaoning|Liaoning province]] ''Confuciusornis'' is the first primitive bird with a [[pygostyle]].
|With its short tail and toothless beak, ''Confuciusornis'' is very modern looking compared to ''[[Archaeopteryx]]''. The toothless beak is however a case of [[convergent evolution]], as more advanced birds retained teeth, illustration the sometimes confusing [[mosaic evolution]] of the dinosaur-bird transition.
|'''Primitive traits'''
* Retained unfused clawed digits, no [[alula]]
* Sideways-facing glenoid joint
'''Derived traits'''
* Short tail with fused vertebrae at the end ([[pygostyle]])
* Larger sternum with a low primitive [[Keel (bird)|keel]]
*Unlike other early birds ''Confuciusornis'' had a toothless beak
| [[File:Confuciusornis sanctus (2).jpg|150px]]
|-
| 115 Ma
|
'''Genus:'''
* ''[[Eoalulavis]]''
|Primitive bird and possibly a descendant of "urvogels" like ''Archaeopteryx''. First bird to possess an [[alula]].
|
|'''Plesiomophic traits'''
* Two unfused, functional digits remain on second and third digit
'''Derived traits'''
* First digit bearing an [[alula]] rather than claw
|
|-
| 93.5–75 Ma
|
'''Genus:'''
* ''[[Ichthyornis]]''
|Considered a close relative to the ancestor to modern birds
|A flying bird found in several epochs in the late Cretaceous which still bore teeth, but in most respects very similar to [[Modern birds|Neornithes]].
|'''Primitive traits'''
* Numerous sharp teeth in much of the beak
'''Derived traits'''
* Fused bones ([[metacarpal]]s) II & III of the hand
* Rigid ribcage with a well-developed [[keel (bird anatomy)|carina]]
* No functional [[claw]]s on the hand
* Short childhood with distinct adult stage.<ref name=chinsamyetal1998>{{cite journal |author1=Chinsamy A. |author2=Martin L.D. |author3=Dobson P. |year=1998 |title=Bone microstructure of the diving ''Hesperornis'' and the volant ''Ichthyornis'' from the Niobrara Chalk of western Kansas |journal=Cretaceous Research |volume=19 |issue=2 |pages=225–235 |doi=10.1006/cres.1997.0102|doi-access=free }}</ref>
| [[File:Ichthyornis yale.JPG|150px]]
|}
 
==Bird evolution==
{{Expand list|date=May 2010}}
{|class="wikitable" style="margin:auto; width:100%;"
|-
! colspan="6" style="text-align:center;"|'''The ''[[Bird]]'' Evolutionary Series'''
|-
! Appearance
! Taxa
! Relationships
! Status
! Description
! Image
|-
| 60–58 Ma
|
'''Genus:'''
* ''[[Waimanu]]''
|
|
|
The earliest-known [[penguin]].
| [[File:Waimanu BW.jpg|150px]]
|-
| ??? Ma
|
'''Genus:'''
* ''[[Elornis]]''
|
|
|An early [[flamingo]].
|
|-
| ??? Ma
|
'''Genus:'''
* ''[[Colymboides]]''
|
|
|An early [[gaviiformes|gaviiform]].
|
|-
| 55–48 Ma
|
'''Genus:'''
* ''[[Mopsitta]]''
|
|
|An early [[psittacine]].
|
|-
| ??? Ma
|
'''Genus:'''
* ''[[Masillaraptor]]''
|
|
|A basal [[falconiform]].
|[[File:Masillaraptor restoration.jpeg|alt=Life restoration based on modern falconiformes|thumb]]
|-
| 50 Ma
|
'''Genus:'''
* ''[[Primapus]]''
|
|
|An early [[apodiform]].
|
|}
 
==Non-mammalian synapsids to mammals==
{{Further|Synapsid}}
{{Further|Mammal}}
{|class="wikitable" style="margin:auto; width:100%;"
|-
! colspan="6" style="text-align:center;"|'''The ''[[Synapsids]]'' → ''[[Mammals]]'' Evolutionary Series'''
|-
! Appearance
! Taxa
! Relationships
! Status
! Description
! Image
|-
| 318-315 Ma
|
'''Genus:'''
* ''[[Protoclepsydrops]]''
|
|Known from very fragmentary finds, ''Protoclepsydrops'' may be the earliest [[synapsid]]
|A low-slung, lizard-like animal of moderate size.
|
|-
| 306 Ma
|
'''Genus:'''
* ''[[Archaeothyris]]''
|
|The oldest undisputed [[synapsid]]
|'''Primitive traits'''
* A relatively flat, reptile-like skull
* Typically reptilian sprawling gait
* Generally lizard-like proportions with a [[Anatomical terms of ___location#Dorsal and ventral|dorso-ventrally]] flattened body
'''Derived traits'''
* Temporal opening low on the side of the [[skull roof]], between the [[zygomatic bone]] and the elements above.
* Tendency to enlarged forward teeth on the [[maxilla]]
|[[File:Archaeothyris BW.jpg|150px]]
|-
| 297 Ma
| '''Genus:'''
* ''[[Haptodus]]''
| A primitive member of the [[Sphenacodontidae]], or possibly just outside the group.<ref>{{cite journal |author=Jörg Fröbisch |author2=Rainer R. Schoch |author3=Johannes Müller |author4=Thomas Schindler |author5=Dieter Schweiss |year=2011 |title=A new basal sphenacodontid synapsid from the Late Carboniferous of the Saar-Nahe Basin, Germany |url=http://www.app.pan.pl/archive/published/app56/app20100039.pdf |journal=Acta Palaeontologica Polonica |volume=56 |issue=1 |pages=113–120 |doi=10.4202/app.2010.0039|s2cid=45410472 |doi-access=free }}</ref><ref name=CutleriaRev>{{cite journal |author=Michel Laurin |year=1994 |title=Re-evaluation of ''Cutleria wilmarthi'', an Early Permian synapsid from Colorado |url=https://mnhn.academia.edu/MichelLaurin/Papers/1242256/Re-evaluation_of_Cutleria_wilmarthi_an_Early_Permian_synapsid_from_Colorado |journal=Journal of Vertebrate Paleontology |volume=14 |issue=1 |pages=134–138 |doi=10.1080/02724634.1994.10011544}}</ref>
|A [[pelycosaur]]-grade synapsid
|'''Derived traits'''
* Two or three moderately large canine-like teeth about a third down the [[maxilla]].<ref>{{cite journal|last=Romer|first=A.S.|author2=Price, L.L. |title=Review of the Pelycosauria|journal=Special Papers of the Geological Society of America|year=1940|volume=28|pages=1–538|doi=10.1130/spe28-p1|series=Geological Society of America Special Papers}}</ref>
* [[Dentary]] bone the largest element of the lower jaw<ref name=CutleriaRev/>
* The skull deeper than in ''[[Archaeothyris]]''
|[[File:Haptodus BW.jpg|150px]]
|-
| 295 Ma
|
'''Genus:'''
* ''[[Dimetrodon]]''
|An advanced member of the family [[Sphenacodontidae]], from which the [[therapsid]]s (advanced synapsids) evolved
|A [[pelycosaur]]-grade synapsid. At up to 4 meters, ''Dimetrodon'' was one of the largest animals of its time. The distinct sail of the back makes it the most recognized synapsid known
|
'''Primitive traits'''
* Cold blooded metabolism dependent of external heat source (hence the "sail")<ref>{{cite journal |last1=GA Floridesa |first1=Kalogiroua SA |last2=SA |last3=Wrobelb |first3=L Tassoub |year=2001 |title=Natural environment and thermal behavior of ''Dimetrodon limbatus'' |journal=Journal of Thermal Biology |volume=26 |issue=1 |pages=15–20 |doi=10.1016/S0306-4565(00)00019-X |pmid=11070340}}</ref>
* Sprawling gait
* No secondary palate
* No enlarged side teeth in the lower jaw
'''Derived traits'''
* Distinctly elongated 2nd and 3rd tooth on the [[maxilla]], corresponding to the [[canine tooth|canine]] in mammals. The first canine generally longer than the second.<ref name="Angielczyk">{{cite journal | last1 = Angielczyk | first1 = Kenneth D. | title = ''Dimetrodon'' Is Not a Dinosaur: Using Tree Thinking to Understand the Ancient Relatives of Mammals and their Evolution | journal = Evolution: Education and Outreach | volume = 2 | issue = 2| pages = 257–271 | doi = 10.1007/s12052-009-0117-4 | date = June 2009 | doi-access = free }}
</ref>
* Skull deep and narrow
* Body overall deeper than in earlier forms
| [[File:Dimetrodon skeleton.jpg|150px]]
|-
| 267 Ma
|
'''Genus:'''
* ''[[Biarmosuchus]]''
|
|A primitive [[therapsid]]. About the size of a large dog, ''Biarmosuchus'' was a lightly built and likely fairly agile animal for its size.<ref name=Palaeos-Biarmosuchus>White, T. & Kazlev, M. A. (2009): [http://palaeos.com/vertebrates/therapsida/biarmosuchidae.html Therapsida: Biarmosuchia: Biarmosuchidae / Eotitanosuchidae], from [[Palaeos]] website.</ref>
|
'''Primitive traits'''
* No [[respiratory turbinate]]s indicate limited overall oxygen consumption and hence [[Bradymetabolism|bradymetaboliic]] metabolism<ref>{{cite book |last=Ruben |first=J.A. |author2=Hillenius, W.J. |author3=Kemp, T.S. |author4=Quick, D.E. |year=2011 |chapter=The Evolution of Mammalian Endothermy |title=Forerunners of Mammals |editor=Chinsamy-Turan, A. |publisher=Indiana University Press |___location=Bloomington |isbn=978-0-253-35697-0 |pages=272–286 |chapter-url=https://books.google.com/books?id=cp26-CA2CDUC&q=forerunners%20of%20the%20mammals&pg=PA3}}</ref>
* Sprawling legs, but the legs longer and more slender than in pelycosaurs<ref name=Palaeos-Biarmosuchus/>
* Long [[pelycosaur]]-like tail
'''Derived traits'''
* A single canine as the first tooth on the [[maxilla]], all other maxillary teeth small
* Tendency for an enlarged caninelike tooth on the [[dentary]]
* Internal nostrils covered by a partial fleshy [[palate]]<ref>{{cite journal|last=Maier|first=W.|author2=Heever, J. |author3=Durand, F. |title=New therapsid specimens and the origin of the secondary hard and soft palate of mammals|journal=Journal of Zoological Systematics and Evolutionary Research|date=27 April 2009|volume=34|issue=1|pages=9–19|doi=10.1111/j.1439-0469.1996.tb00805.x|doi-access=free}}</ref>
* Enlarged temporal opening giving more powerful bite
| [[File:Biarmosuchus.jpg|150px]]
|-
| 247–237 Ma
| '''Genus:'''
* ''[[Cynognathus]]''
|An advanced synapsid
|All species of ''Cynognathus'' were rather heavyset carnivores about a meter in length and with a sprawling gait and heavy jaws.
|'''Primitive traits'''
*No bony palate
*No differentiated cheek teeth
'''Derived traits'''
*Teeth clearly differentiated into [[incisor]]s, [[Canine tooth|canines]] and cheek teeth in both upper and lower jaws
*Cheek teeth with multiple cusps
| [[File:Cynognathus.JPG|150 px]]
|-
| 248–245 Ma
|
'''Genus:'''
* ''[[Thrinaxodon]]''
|A small bodied relative of the larger ''[[Cynognathus]]''.
|An advanced non-mammalian [[cynodont]]. A burrower that ranged from the size of a [[marten]] to a [[badger]].
|'''Primitive traits'''
* While the [[dentary]] dominated the lower jaw, the hinge was between the [[articulare]] and [[Quadrate bone|quadrate]].<ref>{{cite book|last=Czaplewski|first=Terry A. Vaughan, James M. Ryan, Nicholas J.|title=Mammalogy|year=2000|publisher=Brooks/Cole Thomson Learning|___location=Fort Worth|isbn=978-0030250347|page=51|url=https://books.google.com/books?id=LD1nDlzXYicC&q=Thrinaxodon+jaw+joint&pg=PA51|edition=4th}}</ref>
* Teeth even at very young age with no [[Occlusion (dentistry)|occlusion]], indicating no or limited [[lactation]] and hence slow growth.
* No [[Harderian gland]], indicating lack of fur and hence limited enothermy.<ref>{{cite journal|last1=Ruben|first1=J. A.|title=Selective Factors Associated with the Origin of Fur and Feathers|journal=Integrative and Comparative Biology|date=1 August 2000|volume=40|issue=4|pages=585–596|doi=10.1093/icb/40.4.585|doi-access=free}}</ref> May have had [[whiskers]]
'''Derived traits'''
* Well developed respiratory turbinates and palate, indicating [[homeothermy]]
* Generally mammal-like dentition.
* Mammal-like ecology: burrowing and small size
* Animals of different sizes found together, indicating post-hatching [[Parental investment|parental care]].
| [[File:Thrinaxodon Lionhinus.jpg|150px]]
|-
| 205 Ma
|
'''Genus:'''
* ''[[Morganucodon]]''
|A smaller, more shrew-like relative of ''[[Thrinaxodon]]'' and ''[[Sinoconodon]]''
|An early mammal, possibly representing the earliest lactating animals, but outside the [[crown group]] (a [[mammaliform]])
|'''primitive traits'''
* Semi-sprawling gait
* [[Articular bone|Articular]] and [[quadrate bone]]s still forming a small jaw articulation, though main joint being the between the [[dentary]] and [[squamosal bone]]
* Large number of teeth
'''Advanced traits'''
* Only two sets of teeth with full [[Occlusion (dentistry)|occlusion]]. No teeth in infancy, indication [[lactation]]
* Short mammalian-type lifespan
* Presence of [[Harderian gland]], indication [[fur|pelage]] and hence endothermy
|[[File:Morganucodon.jpg|150px]]
|-
| 125 Ma
|
'''Genus:'''
* ''[[Yanoconodon]]''
|One of the [[Triconodonts]]
|An early [[crown group]] mammal.
|'''Primitive traits'''
* Long body with 26 [[lumbar vertebrae|lumbar]] and [[thoracic vertebrae]] (only 20 in modern mammals)
* Lumbar vertebrae with [[ribs]]
* [[Articular bone|Articular]] and [[quadrate bone]]s still attached to lower jaw via [[Meckel's cartilage]] (the evolution of the mammalian [[ear ossicle]]s have taken place separately in [[monotremes]] and [[therians]])
'''Advanced traits'''
* Small, very lightly built
* Borrowing
* Insectivorious<ref>{{cite web|title=Press release: Paleontologists Discover New Mammal from Mesozoic Era|url=https://www.nsf.gov/news/news_summ.jsp?cntn_id=108463|publisher=National Science Foundation|language=en|date=14 March 2007}}</ref>
| [[File:Yanoconodon BW.jpg|150px]]
|}
 
==Evolution of mammals==
{{Further|evolution of mammals}}
{|class="wikitable" style="margin:auto; width:100%;"
|-
! colspan="6" style="text-align:center;"|'''The ''[[Mammal]]'' Evolutionary Series'''
|-
! Appearance
! Taxa
! Relationships
! Status
! Description
! Image
|-
| 100–104 Ma
|
'''Genus:'''
* ''[[Kollikodon]]''
|
|
|The earliest known [[monotreme]].
|
|-
|
|
'''Genus:'''
* ''[[Sinodelphys]]''
|
|
|
The oldest [[metatherian]] known.
|[[File:Sinodelphys szalayi.JPG|150px]]
|-
| ?? Ma
|
'''Genus:'''
* ''[[Djarthia]]''
|
|
|
The earliest-known [[marsupial]].
||[[File:Djarthia murgonensis.jpg|150px]]
|-
| 164–165 Ma
|
'''Genus:'''
* ''[[Juramaia]]''
|
|
|
The oldest known [[eutherian]]<ref name=Juramaia>{{cite journal |author=Zhe-Xi Luo |author2=Chong-Xi Yuan |author3=Qing-Jin Meng |author4=Qiang Ji |title=A Jurassic eutherian mammal and divergence of marsupials and placentals |journal=Nature |volume=476 |date=25 August 2011 |pages=442–445 |doi=10.1038/nature10291 |issue=7361|bibcode=2011Natur.476..442L |pmid=21866158|s2cid=205225806 }} [http://www.nature.com/nature/journal/v476/n7361/extref/nature10291-s1.pdf Electronic supplementary material]</ref>
|[[File:Juramaia NT.jpg|150px]]
|-
| 63-50 Ma
|
'''Genus:'''
* ''[[Eritherium]]''
|
|
|
The earliest known [[proboscidean]].
|
|-
| 60–55 Ma
|
'''Genus:'''
* ''[[Miacis]]''
|
|
|
The possible ancestor of the modern order [[Carnivora]].
|[[File:Miacis.jpg|150px]]
|-
| 15.97–11.61 Ma
|
'''Genus:'''
* ''[[Heteroprox]]''
|
|
|
The earliest known [[cervid]].
|[[File:Heteroprox eggeri.JPG|150px]]
|-
| 20–18 Ma
|
'''Genus:'''
* ''[[Eotragus]]''
|
|
|
The earliest known [[bovid]].
|[[File:Eotragus sansaniensis.JPG|150px]]
|-
| 45–40 Ma
|
'''Genus:'''
* ''[[Protylopus]]''
|
|
|
The oldest [[camel]] known, it was also the smallest.
|
|-
| ??? Ma
|
'''Genus:'''
* ''[[Hyrachyus]]''
|
|
|
Suspected to be the ancestor of modern [[tapirs]] and [[rhinoceroses]].
|[[File:Hyrachyus.png|150px]]
|-
| 55.4–48.6 Ma
|
'''Genus:'''
* ''[[Heptodon]]''
|
|
|
Suspected to be the ancestor of modern [[tapirs]].
|[[File:Heptodon posticus.jpg|150px]]
|-
| 38–33.9 Ma
|
'''Genus:'''
* ''[[Hesperocyon]]''
|
|
|
The earliest known [[canid]].
|[[File:Hesperocyon Gregarius.jpg|150px]]
|-
| ??? Ma
|
'''Genus:'''
* ''[[Eurymylus]]''
|
|
|
The earliest known [[lagomorph]].
|
|-
| 52.5 Ma
|
'''Genus:'''
* ''[[Onychonycteris]]''
|
|
|
One of the two oldest known [[Monotypic taxon|monospecific]] genera of [[bat]].
|
|-
| 11.6 Ma
|
'''Genus:'''
* ''[[Kretzoiarctos]]''
|
|
|
The earliest known member of the [[giant panda]] clade.<ref>{{cite journal | vauthors = Abella J, Alba DM, Robles JM, Valenciano A, Rotgers C, Carmona R, Montoya P, Morales J | title = Kretzoiarctos gen. nov., the oldest member of the giant panda clade | journal = PLOS ONE | volume = 7 | issue = 11 | pages = e48985 | date = 2012-11-14 | pmid = 23155439 | pmc = 3498366 | doi = 10.1371/journal.pone.0048985 | bibcode = 2012PLoSO...748985A | doi-access = free }}</ref>
|
|-
| 63–61.7Ma
|
'''Genus:'''
* ''[[Purgatorius]]''
|
|
|Believed to be the earliest example of a [[primate]] or a proto-primate, a primatomorph precursor to the [[Plesiadapiformes]].
|[[File:Purgatorius BW.jpg|200px]]
|-
| 12.5–8.5 Ma
|
'''Genus:'''
* ''[[Sivapithecus]]''
|
|
|
This genus may have been the ancestor to the modern [[orangutan]]s.
|[[File:Sivapithecus.jpg|150px]]
|-
| 16–8 Ma
|
'''Genus:'''
* ''[[Kenyapotamus]]''
|
|
|A possible ancestor of living [[hippopotamid]]s.
|
|-
| 47 Ma
|
'''Genus:'''
* ''[[Eomanis]]''
|
|
|The earliest known true (and scaled) [[pangolin]].
|[[File:Eomanis waldi 1.JPG|150px]]
|}
 
==Early artiodactyls to whales==
{{Further|evolution of whales}}
{|class="wikitable" style="margin:auto; width:100%;"
|-
! colspan="6" style="text-align:center;"|'''The ''[[whale]]'' Evolutionary Series'''
|-
! Appearance
! Taxa
! Relationships
! Status
! Description
! Image
|-
|50–48 Ma
|
'''Genus:'''
* ''[[Pakicetus]]''
|
|
|
| [[File:Skull Pakicetus inachus.jpg|150px]]
|-
|48–47 Ma
|
'''Genus:'''
* ''[[Ambulocetus]]''
|
|
|
| [[File:Ambulocetus et pakicetus.jpg|150px]]
|-
|46 Ma
|
'''Genus:'''
* ''[[Kutchicetus]]''
|
|
|
| [[File:Kutchicetus BW.jpg|150px]]
|-
|47 Ma
|
'''Genus:'''
* ''[[Artiocetus]]''
|
|
|
|
|-
|41–33 Ma
|
'''Genus:'''
* ''[[Dorudon]]''
|
|
|
| [[File:Dorudon atrox Senckenberg.jpg|150px]]
|-
|25 Ma
|
'''Genus:'''
* ''[[Aetiocetus]]''
|
|
|
|[[File:Aetiocetus BW.jpg|150px]]
|-
|40–34 Ma
|
'''Genus:'''
* ''[[Basilosaurus]]''
|
|
|
| [[File:Basilosaurus skeleton.jpg|150px]]
|-
|8–15 Ma
|
'''Genus:'''
* ''[[Eurhinodelphis]]''
|
|
|
| [[File:Eurhinodelphis longirostris.jpg|150px]]
|-
|26 Ma
|
'''Genus:'''
* ''[[Mammalodon]]''
|
|
|
|[[File:Mammalodon.jpeg|150px]]
|}
 
==Evolution of sirenians==
{{Further|evolution of sirenians}}
{| class="wikitable" style="margin:auto; width:100%;"
|-
! colspan="6" style="text-align:center;"|'''The ''[[Sirenia]]'' Evolutionary Series'''
|-
! Appearance
! Taxa
! Relationships
! Status
! Description
! Image
|-
| 50 Ma
|
'''Genus:'''
* ''[[Pezosiren]]''
|
|
|
Fossil evidence suggest that it had well developed hips and hind legs. It might lived a semi-aquatic life similar that of a [[hippopotamus]].
|[[File:Dans l'ombre des dinosaures - Pezosiren - 016.jpg|150px]]
|-
| 40 Ma
|
'''Genus:'''
* ''[[Prorastomus]]''
|
|
|
|
[[File:Prorastomus BW.jpg|150px]]
|-
| ??? Ma
|
'''Genus:'''
* ''[[Protosiren]]''
|
|
|
|
|-
|48.6–33.9 Ma
|
'''Genus:'''
* ''[[Eotheroides]]''
|
|
|
An early member of [[dugongidae]].
|[[File:Eotheroides sp.JPG|150px]]
|-
|??? Ma
|
'''Genus:'''
* ''[[Halitherium]]''
|
|
|
|
[[File:Halitherium.jpg|150px]]
|}
 
==Evolution of pinnipeds==
{{Further|pinniped}}
{|class="wikitable" style="margin:auto; width:100%;"
|-
! colspan="6" style="text-align:center;"|'''The ''[[Pinniped]]'' Evolutionary Series'''
|-
! Appearance
! Taxa
! Relationships
! Status
! Description
! Image
|-
| 21 to 24 Ma
|
'''Genus:'''
* ''[[Puijila]]''
|
|
|
Likely had webbed feet, along with some skull similarities to modern pinnipeds.
|
[[File:Puijila darwini (white background).jpg|200px]]
|-
| 23-11 Ma
|
'''Genus:'''
* ''[[Potamotherium]]''
|
|
| A very basal pinniped.
|[[File:Potamotherium.jpg|200px]]
|-
| 24–22 Ma
|
'''Genus:'''
* ''[[Enaliarctos]]''
|
|
| An early seal, but with more primitive skull and feet.
|
[[File:Enaliarctos mealsi.JPG|200px]]
|}
 
==Evolution of the horse==
{{Further|evolution of the horse}}
{|class="wikitable" style="margin:auto; width:100%;"
|-
! colspan="6" style="text-align:center;"|'''The ''[[Hyracotherium]]'' → ''[[Equus (genus)|Equus]]'' Evolutionary Series'''
|-
! Appearance
! Taxa
! Relationships
! Status
! Description
! Image
|-
|60–45 Ma
|
'''Genus:'''
* ''[[Hyracotherium]]''
|
|
|
| [[File:HyracotheriumVasacciensisLikeHorse.JPG|150px]]
|-
|40–30 Ma
|
'''Genus:'''
* ''[[Mesohippus]]''
|
|
|
| [[File:Mesohippus Bairdii.jpg|150px]]
|-
|20 Ma
|
'''Genus:'''
* ''[[Parahippus]]''
|
|
|
| [[File:Parahippus Cognatus.jpg|150px]]
|-
|17–11 Ma
|
'''Genus:'''
* ''[[Merychippus]]''
|
|
|
| [[File:Anchitherium.jpg|150px]]
|-
|12 Ma
|
'''Genus:'''
* ''[[Pliohippus]]''
|
|
|
| [[File:Pliohippus Pernix.jpg|150px]]
|-
|1.8–0 Ma
|
'''Genus:'''
* ''[[Equidae|Equus]]''
|
|
|
| [[File:Img 3372 Me trot.jpg|150px]]
|}
 
==Human evolution==
{{Further|Timeline of human evolution}}[[List of human evolution fossils]]
{|class="wikitable" style="margin:auto; width:100%;"
|-
! colspan="6" style="text-align:center;"|'''The [[Human]] Evolutionary Series'''
|-
! Appearance
! Taxa
! Relationships
! Status
! Description
! Image
|-
|36–32 Ma
|
'''Genus'''
* ''[[Apidium]]''
|The oldest primitive monkey known in the fossil record, dating back before the split between Old and New World monkeys.
|Basal to both Old and New World monkeys.
|'''Primitive traits'''
* Smaller canines than later monkeys such as ''[[Parapithecus]]''
* Retains some post-cranial characters seen in prosimians
'''Derived traits'''
* Fused mandibular symphysis
* Scapula similar to modern squirrel monkeys
* Low rounded molar cusps rather than high cusps as is seen in [[tarsier]]s and [[strepsirrhine]]
|
|-
|33 Ma
|
'''Genus'''
* ''[[Aegyptopithecus]]''
|A Miocene monkey which bridges the gap between the Eocene ancestors of [[Old World monkeys]] and Miocene ancestor of [[Hominoidea]].
|Tentatively positioned transitional form prior to the Old World monkey/ape split.
|'''Primitive traits'''
* Retained auditory features similar to Old World monkeys
* Incapable of true [[brachiation]] unlike extant apes
* Reduced capitular tail, but was proportionally smaller than ''[[Apidium]]''
'''Derived traits'''
* Ape-like teeth including broad, flat incisors and sexually dimorphic canines
* A low sagittal keel and strong temporalis muscles
* Increased size in the visual cortex
|[[File:Aegyptopithecus NT.jpg|150px]]
|-
|27–14 Ma
|
'''Genus'''
* ''[[Proconsul (mammal)|Proconsul]]''
|This primate exhibits very ape-like features like its teeth, but much of its post-cranial remains are more similar to monkeys.
|Universally accepted to be intermediate between 'ape-like monkeys' such as ''Aegyptopithecus'' and later apes including hominids.
|'''Primitive traits'''
* Monkey-like wrist
* Narrow, monkey-like [[ilium (bone)|ilium]]
'''Derived traits'''
* Completely lacked a fully formed tail
* 5-Y pattern on lower molar cusps as also seen in hominoids
| [[File:Proconsul africanus.JPG|150px]]
|-
|13 Ma
|
'''Genus:'''
* ''[[Pierolapithecus]]''
|A European ape which is considered to be the predecessor of the great apes.
|Some objections have been raised to this fossils status due to its ___location in Spain, but ''Pierolapithecus'' is likely a transitional taxon between generalized apes and the lineage which led to great apes.
|'''Pleisomorphic traits'''
* Relatively short fingers and walked in a similar quadrupedal fashion like baboons
* Lacks adaptations for both gibbon-style brachiation as well as derived knuckle-walking like in chimpanzees and gorillas
'''Derived traits'''
* Flat, wider rib cage like great apes for tree-climbing
* The clavicle is large and similar to modern chimps suggesting a dorsally positioned scapula
|
|-
|4.4 Ma
|
'''Genus:'''
* ''[[Ardipithecus]]''
|A woodland hominid adapted to quadruped arboreal locomotion, but also for bipedalism.
|Intermediate between the last common ancestor of chimps and humans, and the [[Australopithecus|australopithecines]].
|'''Primitive traits'''
* Brains smaller than later hominids ranging from about 300-350&nbsp;cc
* Foot thumb is not retracted into the foot as a [[hallux|'big toe']]
* Phalanges are more heavily curved than in ''[[Australopithecus]]''
'''Derived traits'''
* Reduced size in canines, however still retained dimorphic characters
* Hind leg dominant, bipedal locomotion while walking, however were quadrupedal while climbing trees
|[[File:Ardi.jpg|150px]]
|-
|4.4–2.0 Ma
|
'''Genus:'''
* ''[[Australopithecus]]''
|First known genus of fully bipedal apes which are probably ancestral to [[Paranthropus|robust australopiths]] and the genus ''[[Homo]]''.
|Intermediate between extinct quadrupedal and bipedal apes. While the relationship between some species are being revised, ''[[Australopithecus afarensis]]'' is considered to be, by most experts, the ancestor to all later hominids.
|'''Primitive traits'''
* Some species retain a [[sagittal crest]]
* Curved phalanges, indicating semi-arboreal lifestyle
* Semisectorial premolar is present
* Prognathic face to varying degrees
'''Derived traits'''
* Fully bipedal as indicated by many features including the knee joint, hips, lumbar curve in the spine, position of the [[foramen magnum]], and feet
* Increase in brain size ranging from about 375-500&nbsp;cc
* Development of a parabolic jaw
| [[File:Australopithecus africanus - Cast of taung child Face.jpg|150px]]
|-
|2.3–1.4 Ma
|
'''Species:'''
* ''[[Homo habilis]]''
|An early human which is the morphological link between [[australopithecine]]s and later human species.
|Perfect intermediate between early hominids and later humans, possibly ancestral to modern humans.
|'''Primitive traits'''
* Pronounced brow ridge
* Foramen magnum is not positioned as anteriorly like in modern humans, giving a slightly semi-erect appearance
* Although reduced in size the teeth are still fairly large
'''Derived traits'''
* Increase brain size ranging from 510 to 800&nbsp;cc
* Face is slightly prognathic, but at a much steeper angle
* Bulge in the Broca area, possibly the first hominid to use rudimentary speech
* Associated with the first use of stone tools
| [[File:Homo habilis.jpg|150px]]
|-
|2.0–1.0 Ma
|
'''Species:'''
* ''[[Homo erectus]]''
|Very successful hominid, which was probably ancestral to both modern [[humans]] and [[neanderthals]]. Probably the first hominid to leave and successfully colonize territories outside of Africa.
|Ancestral to modern humans and neanderthals.
|'''Primitive traits'''
* Still retains a heavy brow ridge and [[nuchal torus]]
* Lacked the complexity of modern human language, but does show increase in the Broca area
* Thicker bones and larger teeth than modern humans
'''Derived traits'''
* Rounder and larger brain (about 900–1,100&nbsp;cc) than ''H. habilis''
* Face is orthognathic compared to ''H. habilis''
* Probably lived in [[band societies|bands]] and was an active group hunter
* Associated with advanced stone tools and possibly the first hominid to use and produce fire
| [[File:Homo erectus tautavelensis.jpg|150px]]
|-
|500 Ka–recent
|
'''Species'''
* ''[[Archaic humans|Homo rhodesiensis]]''
|''Homo rhodesiensis'' was the immediate ancestor of modern humans which evidently displaced the [[neanderthal]]s in Europe and the island [[Homo floresiensis|'hobbits']] of southeast Asia. ''H. rhodesiensis'' evolved from ''[[Homo erectus]]'' about half a million years ago but still retains some primitive characteristics such as relatively thick bones and molars larger than modern humans.
|Ancestral to modern humans.
|'''Primitive traits'''
* Large teeth
* Heavy brow ridge
* Extremely robust build in most groups
'''Derived traits'''
* Rounder, less broad based cranium
* Larger brain size, approaching (and sometimes exceeding) modern values
| [[File:Skhul.JPG|150px]]
|}
 
==See also==
{{Portal|Paleontology|Science|Evolutionary biology}}
* [[Chimpanzee genome project#Genes of the chromosome 2 fusion site]]
* [[List of fossil sites]] ''(with link directory)''
* [[List of human evolution fossils]]
* [[Transitional fossil]]
 
==References==
{{reflist}}
 
==External links==
* [http://vuletic.com/hume/cefec/#5 Vuletic.com], Section V: Paleontology – Transitional fossils between every animal group
* [https://web.archive.org/web/20050409133626/http://www.palaeos.com/vertebrates/Units/140Sarcopterygii/140.000.html Palaeos.com], Palaeos vertebrates starting with lobe-finned fish (very comprehensive)
* [http://www.talkorigins.org/faqs/faq-transitional.html Talk.origins.org], FAQ: Transitional vertebrate fossils
* [http://transitionalfossils.com/ (A few) transitional fossils]
 
{{DEFAULTSORT:Transitional Fossils}}
[[Category:Transitional fossils|*]]
[[Category:Lists of prehistoric animals]]
Retrieved from "https://en.wikipedia.org/wiki/List_of_transitional_fossils"