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Portlandemys mcdowelli

Reptilia - Testudines - Plesiochelyidae

Taxonomy
Portlandemys mcdowelli was named by Gaffney (1975). Its type specimen is BMNH R2914, a skull (nearly complete skull lacking both lateral temporal regions and left cheek. Mandible lacking posterior portions), and it is a 3D body fossil. Its type locality is Isle of Portland (Portlandemys type locality), which is in a Tithonian marine limestone in the United Kingdom.

Synonymy list
YearName and author
1975Portlandemys mcdowelli Gaffney pp. 15-16 fig. 13
2013Portlandemys mcdowelli Pérez-García and Murelaga
2014Portlandemys mcdowelli Perea et al.
2017Portlandemys mcdowelli Anquetin et al.

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RankNameAuthor
kingdomAnimalia()
Triploblastica
Nephrozoa
Deuterostomia
phylumChordataHaeckel 1847
subphylumVertebrata
superclassGnathostomata
Osteichthyes()
Sarcopterygii
subclassDipnotetrapodomorpha(Nelson 2006)
subclassTetrapodomorpha()
Tetrapoda()
Reptiliomorpha
RankNameAuthor
Anthracosauria
Batrachosauria()
Cotylosauria()
Amniota
Sauropsida
classReptilia
Testudinata(Oppel 1811)
orderTestudinesBatsch 1788
Thalassochelydia
familyPlesiochelyidaeRütimeyer 1873
genusPortlandemys
speciesmcdowelli

If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.

Diagnosis
ReferenceDiagnosis
J. Anquetin et al. 2017Portlandemys mcdowelli can be diagnosed as a “ple- siochelyid” and a representative of Portlandemys by the full list of cranial characters provided for these taxa above. Portlandemys mcdowelli differs from Portlandemys gracilis by having a more robust cranium, a strong processus trochlearis oticum formed equally by the quadrate and prootic, a midline contact of the prefrontals preventing a nasal-frontal contact on the dorsal sur- face of the skull roof, the presence of a ridge closing the ptery- goid fossa posteriorly, foramen posterius canalis carotici interni located close to the basisphenoid-pterygoid suture on the pos- teromedial part of the pterygoid, absence of a raised pedestal on the dorsal surface of the pterygoid contacting the processus interfenestralis of the opisthotic, basisphenoid triangular in out- line in ventral view, a more robust mandible with a high profile in lateral view, strongly developed lingual ridges on the mandible, a symphyseal region more pointed anteriorly as seen in dorsal view, presence of a strong symphyseal hook, and a more trapezoidal splenial.