Pliopithecoidea: Difference between revisions

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The pliopithecoid fossil record mostly consists of teeth with a few mandibular and maxillary fragments.<ref name="Begun2002" /><ref name="Harrison2013" /> The dental formula (2.1.2.3) and shape of the teeth are the primary factors which include pliopithecoids among the [[catarrhini]]. Although some authors have argued that the narrow upper molars and broad upper molars of pliopithecoids demonstrate their affinity with modern catarrhines,<ref name="Harrison&Gu1999">{{cite journal|last1=Harrison|first1=Terry|last2=Gu|first2=Yumin|title=Taxonomy and phylogenetic relationships of early Miocene catarrhines from Sihong, China|journal=Journal of Human Evolution|date=1999|volume=37|pages=225–277|url=http://www.sciencedirect.com/science/article/pii/S004724849990310X|doi=10.1006/jhev.1999.0310}}</ref> others have demonstrated that these traits are variable between species.<ref name="Begun2002" /> In fact, pliopithecoids are more similar to [[New World monkey]]s in some aspects of their dentition, including narrow lower incisors (mesiodistally waisted towards the base of the crown).<ref name="Begun2002" /><ref name="Albaetal2010">{{cite journal|last1=Alba|first1=David|last2=Moyà-Solà|first2=Salvador|last3=Malgosa|first3=Assumpció|last4=Casanovas-Vilar|first4=Isaac|last5=Robles|first5=Josep|last6=Almécija|first6=Sergio|last7=Galindo|first7=Jordi|last8=Rotgers|first8=Cheyenn|last9=Bertó Mengual|first9=Juan Vicente|title=A new species of ''Pliopithecus'' Gervais, 1849 (Primates: Pliopithecoidea) from the Middle Miocene (MN8) of Abocador de Can Mata (els Hostalets de Pierola, Catalonia, Spain)|journal=American Journal of Physical Anthropology|date=2010|volume=141|pages=52–75|doi=10.1002/ajpa.21114}}</ref> Many species have what is often referred to as a 'pliopithecine triangle', a subtle set of ridges defining a small triangular shaped pit between the protocone<!--aka protoconid cusp--> and hypocone<!--aka hypoconid cusp--> of the lower molars, but even this trait is variable.<ref name="Begun2002" /><ref name="Harrison1987" /> Instead, the most defining dental trait present in all pliopithecoids is a tall crowned lower third premolar, which is relatively triangular in outline with a comparatively short, vertically oriented mesiobucal face.<ref name="Begun2002" />

The crania of ''P. vindobonesis'', ''Laccopithecus robustus'', ''Pliopithecus zhanxiangi'', and ''Anapithecus hernyaki'' demonstrate that pliopithecoids had relatively large and globular braincases with a projecting snout.<ref name="Begun2002" /><ref name="Andrewsetal1996" /> The snout projects less than the propliopithecoids of North Africa (''i.e.'' ''[[Aegyptopithecus]]''), suggesting some prognathic reduction from the inferred common ancestor of these two primate families. The orbits are widely spaced and the mandible is long and robust, with a relatively broad ramus.<ref name="Begun2002" /> Most importantly, however, pliopithecoids had an incompletely ossified ectotympanic tube. This anatomical feature represents an intermediate stage between what is found in [[platyrrhines]], which do not have an ossified ectotympanic tube, and [[catarrhines]], which have a completely ossified ectoympanicectotympanic tube.<ref name="Begun2002" /><ref name="Harrison2013" /><ref name="Andrewsetal1996" />

Nearly all of what is known about the body proportions and post-cranial morphology of this family are derived from ''Pliopithecus vindobonensis'', as it is the only species for which a complete skeleton has been found.<ref name="Zapfe1958" /> Still, the majority of fossil material indicates that pliopithecoids were medium sized primates, approximately the size of a howler monkey or a gibbon (8&nbsp;kg).<ref name="Albaetal2012">{{cite journal|last1=Alba|first1=David|last2=Moyà-Solà|first2=Salvador|last3=Robles|first3=Josep M.|last4=Galindo|first4=Jordi|title=Brief Communication: The Oldest Pliopithecid Record in the Iberia Peninsula Based on New Material From the Vallès-Penedès Basin|journal=American Journal of Physical Anthropology|date=2012|volume=147|pages=135–140|doi=10.1002/ajpa.21631|pmid=22170401}}</ref> Köhler estimates a slightly higher average weight of 10&nbsp;kg.<ref name="Kohler" /> Post-cranially, pliopithecoids had an interesting mix of platyrrhine and catarrhine traits. The brachial index of ''P. vindobonesis'' (the length of the radius divided by the length of the humerus) is similar to that of a howler monkey, but the crural index (the length of the tibia divided by the length of the femur) is similar to that of a gibbon.<ref name="Begun2002" /> Proportionally, however, the forelimbs of ''P. vindobonesis'' were shorter than their hindlimbs, making them comparable to a baboon. The hands and feet of ''P. vindobonesis'' were long and curved, suggesting that pliopithecoids were adept and agile climbers.<ref name="Begun2002" /><ref name="Zapfe1958" /> The post-crania of ''P. vindobonesis'' also shows that Pliopithecoids had an entepicondylar foramen, which is a primitive trait not found in any other catarrhine primates (extant or extinct).<ref name="Begun2002" /><ref name="Harrison2013" /><ref name="Andrewsetal1996">{{cite book|last1=Andrews|first1=Peter|last2=Harrison|first2=Terry|last3=Delson|first3=Eric|last4=Bernor|first4=Raymond|last5=Martin|first5=L|title=Distribution and Biochronology of European and Southwest Asian Miocene Catarrhines|date=1996|publisher=Columbia University Press|isbn=0-231-08246-0}}</ref> The wrist and hands of pliopithecoids were seemingly much more similar to platyrrhines than to catarrhines, as the carpo-metacarpal joint of the thumb is a modified “hinge joint” compared to the "saddle-like" thumb joint found in Old World monkeys and apes.<ref name="Harrison1987">{{cite journal|last1=Harrison|first1=Terry|title=The phylogenetic relationships of the early catarrhine primates: a review of the current evidence|journal=Journal of Human Evolution|date=1987|volume=16|pages=41–80|doi=10.1016/0047-2484(87)90060-1}}</ref> Pliopithecoids also had a tail.<ref name="Begun2002" /><ref name="Andrewsetal1996" />