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{{Short description|Extinct genus of reptiles}}
{{Automatic taxobox
| taxon = Glyphoderma
| fossil_range = [[Middle Triassic]]
| authority = Zhao ''et al.'', [[2008 in paleontology|2008]]
| type_species = {{extinct}}'''''Glyphoderma kangi'''''
| type_species_authority = Zhao ''et al.'', 2008
| subdivision_ranks = Other species
| subdivision =
*{{extinct}}''G. robusta'' <small>Hu, Jiang & Li, 2019</small><ref>{{cite journal |author1=Jinyuan Hu |author2=Tao Jiang |author3=Zhiguang Li |year=2019 |title=A new species of ''Glyphoderma'' (Reptilia: Placodontia) of Middle Triassic from Fuyuan County, Yunnan Province, China |journal=Journal of Geology |volume=43 |issue=4 |pages=595–598 |url=http://eng.oversea.cnki.net/kcms/detail/detail.aspx?dbCode=cjfq&QueryID=11&CurRec=8&filename=JSDZ201904008&dbname=CJFDLAST2020 |access-date=2020-05-03 |archive-date=2020-09-13 |archive-url=https://web.archive.org/web/20200913000918/http://eng.oversea.cnki.net/kcms/detail/detail.aspx?dbCode=cjfq&QueryID=11&CurRec=8&filename=JSDZ201904008&dbname=CJFDLAST2020 |url-status=dead }}</ref>
}}
'''''Glyphoderma''''' is an extinct [[genus]] of [[placodont]] reptile from the [[Middle Triassic]] of [[China]] with two known species, ''G. kangi'' and ''G. robusta''. It differs from its relative ''[[Psephochelys]]'' in having three, rather than one, fused [[osteoderm]]s on the posterior [[skull]] surface, and has an earlier temporal range, from the [[Ladinian]] epoch rather than the [[Late Triassic]]. Otherwise, it is similar in most respects to the other [[Placochelyidae|plachochelyids]] found in China. The name comes from the [[Ancient Greek|Greek]] 'γλυφος', 'sculpture' and 'δερμα', 'skin' referring to its unique carapace structure. The specific name honours a Mr. Kang Ximin.<ref name="ZLLH08">{{cite journal |last=Zhao |first=L.-J. |author2=Li, C. |author3=Liu, J. |author4=
==Discovery and naming==
The [[holotype]] of ''G. kangi'', an almost complete skeleton, was found in 2008 in Fuyuan, [[Yunnan Province, Republic of China|Yunnan Province]] of central China in the [[Zhuganpo Formation]]. It is preserved in a thick block of [[limestone]], and so the ventral side is not well known. The total length is 873 mm.<ref name="ZLLH08" />
Su et al. (2025) described two new specimens of ''Glyphoderma kangi'', providing new information on the anatomy of the studied placodont.<ref>{{Cite journal |last1=Su |first1=C. X. |last2=Gu |first2=S.-L. |last3=Jiang |first3=D.-Y. |last4=Motani |first4=R. |last5=Rieppel |first5=O. |last6=Tintori |first6=A. |last7=Zhou |first7=M. |last8=Sun |first8=Z.-Y. |year=2025 |title=Two new specimens of ''Glyphoderma kangi'' (Placodontia, Sauropterygia, Reptilia) from the Middle Triassic of South China |journal=Journal of Vertebrate Paleontology |volume=44 |issue=3 |at=e2439530 |doi=10.1080/02724634.2024.2439530}}</ref>
== Features ==
=== Skull ===
''Glyphoderma'''s skull is the shape of an isosceles triangle, with a long narrow [[Rostrum (anatomy)|rostrum]]. The skull is 110.6 mm long and 83.7 mm wide. There are three large osteoderms fused to the [[Temporal bone|temporal]] arch on each side of the skull, which protrude backwards. The suture between the [[maxilla]] and the [[Jugal bone|jugal]] is underneath the posterior part of the [[Orbit (anatomy)|orbit]]. The [[premaxilla]] has a smaller posterior process than in ''[[Placochelys]],'' only reaching the [[Nostril|naris]] while that of ''Placochelys'' reaches the orbit. Most of the other cranial bones are entirely fused, giving ''Glyphoderma'' a very strong skull. The [[temporal fenestrae]] are about twice as large as the orbits, at 37.3 mm long rather than 25.9 mm. There are two blunt [[Tooth|teeth]] in the posterior part of the lower jaw, but most of the [[Mandible|dentary]] lacks teeth entirely as in the other placochelyids.<ref name="ZLLH08" />
=== Carapace ===
The [[carapace]], made up of more than 400 osteoderms, is roughly circular but with small excavations at front and back to allow the [[neck]] and [[tail]] to move around a little more. Its dorsal surface is slightly convex and has a shallow longitudinal groove along the midline. The excavation at the back is biconcave rather than simply concave, and just exposes the [[pelvis]]. The anterior excavation is more open than that of ''Psephochelys.'' The osteoderms that make up the carapace are pentagonal or hexagonal, and are tightly sutured but not fused as they are in ''Psephochelys.'' Around the edge of the carapace, they are more isolated and have drifted away from their original positions. The carapace is very slightly wider, at 262 mm, than it is long (242.8 mm). There are two slightly enlarged osteoderms, one on either side of the anterior excavation, but these are not tuberculiform and are much smaller than those in ''Psephochelys''. All the osteoderms are highly convex and have radial grooves and ridges which are very deep or very high, hence the genus name. They also have many tiny pits.<ref name="ZLLH08" />
=== Vertebrae and tail ===
''Glyphoderma'' has five or six [[cervical vertebrae]], all of which are very flattened and wide, with low [[neural spines]]. Only one [[Thoracic vertebrae|dorsal vertebra]] can be seen beneath the carapace. There are four [[sacral vertebrae]], with distally expanded [[pleurapophyses]] enclosing a [[foramen]] between each pair. 34 [[Vertebra|caudal vertebrae]] are preserved, although some may be missing, and the first three of them have transverse processes.<ref name="ZLLH08" />
=== Front legs ===
Only the distal end of each [[scapula]] is exposed by the carapace, but the [[Humerus|humeri]] are well preserved and exposed, at 65.7 mm long. The distal end of each humerus is expanded, with a flat triangular depression on the dorsal side, and an open [[ectepicondylar groove]] along the anterior margin. The [[ulna]] and [[Radius (bone)|radius]] are of very similar lengths (39.5 and 40.8 mm respectively) but the radius is much thicker. Both ends of the radius have a depression on the dorsal surface. There are five [[ossification]]s in the [[Carpal bones|carpus]], but the [[Hand|manus]] is very poorly preserved and we know almost nothing about it.<ref name="ZLLH08" />
=== Hind legs ===
The [[femur]] is expanded at both ends, but has a short shaft (only 59 mm). The space between the [[tibia]] and [[fibula]] is very large as the tibia has a straight medial edge and a concave lateral one. They are roughly the same length (47.5 mm fibula, 49.4 mm tibia). The [[Calcaneus|calcaneum]] and astragalus form a depression for the distal end of the tibia to fit into. There are four other [[Tarsus (skeleton)|tarsals]] and four [[Metatarsal bones|metatarsals]], but it is very difficult to determine the phalangeal formula due to the poor preservation of the foot.<ref name="ZLLH08" />
==References==
{{
{{Taxonbar|from=Q3772553}}
[[Category:Middle Triassic reptiles of Asia]]
▲{{Sauropterygia|Placodontia}}
[[Category:Sauropterygian genera]]
▲[[Category:Placodonts]]
{{triassic-reptile-stub}}
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