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Bridgeremys pusilla

Reptilia - Testudines - Geoemydidae

Taxonomy
Echmatemys pusilla was named by Hay (1908). Its type specimen is AMNH 5992, a partial skeleton (partial shell), and it is a 3D body fossil. Its type locality is Grizzly Buttes, which is in a Bridgerian terrestrial horizon in the Bridger Formation of Wyoming. It is the type species of Bridgeremys.

It was recombined as Bridgeremys pusilla by Hutchison (2006) and Vlachos (2018).

Synonyms
  • Clemmys morrisiae was named by Hay (1908) ["doubtfully referred to Clemmys " according to Holman and Fritz 2001]. Its type specimen is AMNH 6029 (holotype), a partial shell, and it is a 3D body fossil. Its type locality is Grizzly Buttes, which is in a Bridgerian terrestrial horizon in the Bridger Formation of Wyoming.

    It was considered a nomen dubium by Holman and Fritz (2001); it was synonymized subjectively with Bridgeremys pusilla by Vlachos (2018).
Synonymy list
YearName and author
1908Clemmys morrisiae Hay
1908Echmatemys pusilla Hay pp. 337-339
2006Bridgeremys pusilla Hutchison
2018Bridgeremys pusilla Vlachos

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RankNameAuthor
kingdomAnimalia()
Triploblastica
Nephrozoa
Deuterostomia
phylumChordataHaeckel 1847
subphylumVertebrata
superclassGnathostomata
Osteichthyes()
Sarcopterygii
subclassDipnotetrapodomorpha(Nelson 2006)
subclassTetrapodomorpha()
Tetrapoda()
Reptiliomorpha
Anthracosauria
RankNameAuthor
Batrachosauria()
Cotylosauria()
Amniota
Sauropsida
classReptilia
Testudinata(Oppel 1811)
orderTestudinesBatsch 1788
suborderCryptodira
Pantestudinoidea
superfamilyTestudinoidea
Pangeoemydidae
familyGeoemydidaeTheobald 1868
genusBridgeremys
speciespusilla()

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. H. Hutchison 2006Small turtles (maximum plastron length about 160 mm) with axillary and inguinal musk ducts (Rathke glands); supracaudal scales extend onto suprapygal; osteological evidence of kinesis along hyo-hypoplastral sutures and between hypoplastra and carapace; modal neural-costal contacts = N1(C1), N2(C1-3), N3(C3-4), N4(C4-54), N5(C5-6), N6 (6 OR 6-7), N7(C7 OR 6-7), N8(C7-8); weak to well-defined costal wedging; carapace with low neural carina posteriorly; articulating scars on the costals for the buttresses either flat and raised or convex; portion of epiplastron covered by gular scales sharply offset from the visceral surface in adults; surface of the epiplastra covered by the gular scales is not deeply or broadly concave; entoplastron about as long or longer than broad; posterior buttress contacting C5-6; C6 contacting P7; dorsal junction of rib to C8 contiguous with sacral scar; sharp offset between the start of the anterior marginals and the body cavity; growth annulae on epiplastra and carapacial bones usually well defined; modal pleural-marginal seam formula = 1m], [m5], [m7, [m9, [m11; modal seam formula for the midline length of the plastral scales = abdominal > pectoral > femoral > anal > gular > humeral; modal formula for the midline lengths of the plastral bones = hypoplastron > xiphiplastron > entoplastron > hyoplastron > epiplastron
E. Vlachos 2018Bridgeremys pusilla can be diagnosed as a member of Geoemydidae based on the presence of axillary and inguinal musk duct foramina and paired marginals XII that expand onto suprapygal II. Bridgeremys pusilla differs from all other North American Geoemydidae based on small size, presence of octagonal neurals (II or III) and hexagonal neurals with posterolateral short sides, a possible hinge between the hyo- and hypoplastra, and poorly developed anal notch and axillary and inguinal buttresses.