imported>JJMC89 bot III: Moving :Category:Placodonts to :Category:Placodontia per Wikipedia:Categories for discussion/Speedy

2025-03-30T19:36:50Z

Moving Category:Placodonts to Category:Placodontia per Wikipedia:Categories for discussion/Speedy

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{{Short description|Extinct genus of reptiles}}
{{Refimprove|date=February 2021}}
{{Automatic taxobox
| fossil_range = [[Late Triassic]]
| image = Psephoderma.jpg
| image_caption = ''P. alpinum'' fossil
| taxon = Psephoderma
| authority = [[Christian Erich Hermann von Meyer|Meyer]], 1858
| subdivision_ranks = Species
| subdivision =
* {{extinct}}''P. alpinum'' <small>Meyer, 1858 ([[Type (zoology)|type]])</small>
* {{extinct}}''P. anglicum'' <small>Meyer, 1867</small>
}}'''''Psephoderma''''' (meaning "pebbly skin", from the [[Ancient Greek]] ''psepho'' (ψῆφος), "pebbly", and ''derma'' (δέρμα), "skin") is a genus of [[placodont]]s very similar to the related genera ''[[Placochelys]]'' and ''[[Cyamodus]]''. ''Psephoderma'' had a flattened [[skull]] and a narrow, straight [[rostrum (anatomy)|rostrum]], much narrower than that of its relatives. Inside this [[skull]], embedded in the jaws, were rounded teeth specialized for crushing the [[shellfish]] it ate. Unlike henodontid [[placodont]]s, ''Psephoderma''<nowiki>'</nowiki>s [[carapace]] was divided into two pieces, one on the shoulders and back, and another on the ventral end. ''Psephoderma'' grew to {{convert|180|cm|ft}} long, larger than many of its relatives,<ref>{{cite book
| url = https://books.google.com/books?id=7SU_DwAAQBAJ
| title = The Late Triassic World: Earth in a Time of Transition
| publisher = Springer Nature
| date = 2018
| access-date = 12 September 2022
| page = 281
| author = Lawrence H. Tanner
|isbn = 978-3-319-68008-8
}}</ref> and lived in the Late [[Triassic]] ([[Norian|Norian -]] [[Rhaetian]]), about 210 million years ago. It was one of the last [[placodont]]s to live.{{citation needed|date=July 2019}} Fossils of ''Psephoderma'' have been found in the Rhaetian deposits in the [[Alps]] and in England, hence the specific names.<ref name=":1">{{Cite book|url=https://archive.org/details/cranialanatomyof45riep|title=The cranial anatomy of ''Placochelys placodonta'' Jaekel, 1902, and a review of the Cyamodontoidea (Reptilia, Placodonta)|last=Rieppel|first=Olivier|date=2001|publisher=Field Museum of Natural History}}</ref>

==Description==
[[File:Psephoderma new NT.jpg|thumb|left|Life restoration of ''Psephoderma alpinum'']]
''Psephoderma'' had a long, narrow rostrum, which was the main difference between its skull and those of its relatives. This rostrum bore paired grooves on the inside of the mouth, which led to the [[Choana|internal nares]] and are a diagnostic feature for the genus. The anterior processes of the [[Maxilla|maxillae]] stretched forwards a long way along the rostrum, while the posterior processes of the [[Premaxilla|premaxillae]] stretched a long way back up the rostrum and came between the [[Nostril|external nares]] and between the [[Nasal bone|nasal bones]]. The nasal bones were very small, mere splinters of bone. The [[Orbit (anatomy)|orbits]] were large and somewhat irregularly shaped, and indicate that the [[Eye|eyes]] were on top of the head looking upwards. Its [[pineal foramen]] was large, and anteriorly placed, with its anterior edge bordered by the [[Frontal bone|frontal bones]]. Unlike most of its relatives, its ectopterygoid is not known and may not be present, as in ''[[Protenodontosaurus]].'' The ''P. alpinum'' species had decidedly elongated, posterior, tooth-bearing plates for crushing the [[shellfish]] that formed its diet. No teeth were present along the premaxillae or the rostral area of the maxillae, but four crushing [[Tooth|teeth]] were in each side of the [[palate]], the first three in a triangle of small, rounded teeth and the fourth a short distance behind them. The fourth tooth was huge, far larger than the first three. The lack of teeth near the front of the mouth and rostrum indicate that the elongated rostrum was mainly used for rooting out or digging up shellfish, which would then be taken into the back of the mouth and crushed by the large teeth. ''Psephoderma'''s [[Temporal fossa|temporal fossae]] were narrow, but highly elongated. The posterior process of the [[postorbital bone]]s reached far back into the temporal arches, underneath the temporal fossae. The whole skull was highly ventrodorsally compressed. It had temporal tubercles, but they were small, and restricted solely to the posterior ends of the [[Squamosal bone|squamosal bones]]. Its [[Occipital bone|occiput]] was deeply excavated and its entire [[Neurocranium|braincase]] very small. However, the braincase walls were quite thick and well armoured.<ref name=":1" />

The carapace of ''Psephoderma'' was made up of two parts, one of which covered the [[rib cage]] and [[thorax]] and the other of which covered the [[pelvis]]. Both parts of the carapace were made of partially fused [[Scute|scutes]], roughly hexagonal or circular in shape. Its tail was quite long, up to about 80 cm, and had scutes all the way down it. The limbs were relatively small and would have been used as paddles, but had individual toes rather than a flipper.{{citation needed|date=July 2019}}[[Image:Psephoderma alpinum 1.JPG|thumb|left|''P. alpinum'' shell]]

==References==
<references />

==External links==
*[https://web.archive.org/web/20181227230305/http://www.paleofile.com/Demo/Mainpage/Taxalist/Placodontia.htm Family: PLACOCHELYIDAE], paleofile.com

{{Sauropterygia|P.}}
{{Portal|Paleontology}}
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[[Category:Placodontia]]
[[Category:Late Triassic reptiles of Europe]]
[[Category:Fossil taxa described in 1858]]
[[Category:Fossils of Italy]]
[[Category:Fossils of Israel]]
[[Category:Sauropterygian genera]]

Psephoderma - Revision history

imported>JJMC89 bot III: Moving :Category:Placodonts to :Category:Placodontia per Wikipedia:Categories for discussion/Speedy