PBDB Taxon

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Axestemys splendidus

Reptilia - Testudines - Trionychidae

Taxonomy

Aspideretes splendidus was named by Hay (1908). Its type specimen is AMNH 3952, a partial shell (a large, but somewhat imperfect, carapace), and it is a 3D body fossil.

It was recombined as Aspideretoides splendidus by Gardner et al. (1995) and Gardener (1995); it was recombined as Eugenechelys splendidus by Chkhikvadze (2000); it was recombined as Axestemys splendida by Vitek (2012); it was recombined as Axestemys splendidus by Vitek (2012) and Vitek and Joyce (2015).

Synonyms

Aspideretes granifer was named by Hay (1909). Its type specimen is USNM V 5736, a partial skeleton, and it is a 3D body fossil. Its type locality is Cow Island (USNM 5736), which is in a Campanian/Campanian terrestrial horizon in the Judith River Formation of Montana.

It was synonymized subjectively with Aspideretoides splendidus by Gardner et al. (1995); it was synonymized subjectively with Axestemys splendidus by Vitek and Joyce (2015).
Aspideretes planus was named by Parks (1933). Its type specimen is ROM 815, a carapace, and it is a 3D body fossil. Its type locality is 3 miles southeast of Steveville, which is in a Campanian terrestrial horizon in Canada.

It was synonymized subjectively with Aspideretoides splendidus by Gardner et al. (1995); it was synonymized subjectively with Axestemys splendidus by Vitek and Joyce (2015).

Synonymy list

Year	Name and author
1908	Aspideretes splendidus Hay p. 491 figs. Plate 88, figs. 7, 8, 9; plate 91; text-fig. 646
1909	Aspideretes granifer Hay p. 168 figs. Plate XXVII, figs. 4, 5
1930	Aspideretes granifer Hay p. 109
1930	Aspideretes splendidus Hay p. 109
1933	Aspideretes planus Parks p. 28 figs. Pl. 8:3
1995	Aspideretoides splendidus Gardener p. 636 figs. 2B, 2C, 3B-3D, 4B, 4C, 6
1995	Aspideretoides splendidus Gardner et al.
2000	Eugenechelys splendidus Chkhikvadze
2012	Axestemys splendidus Vitek
2012	Axestemys splendida Vitek pp. 12-19 figs. 7, 8, 9, 10, 11
2015	Axestemys splendidus Vitek and Joyce

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Rank	Name	Author
kingdom	Animalia	()
—	Bilateria
—	Eubilateria	Ax 1987
—	Deuterostomia
phylum	Chordata	Haeckel 1874
subphylum	Vertebrata
superclass	Gnathostomata
—	Osteichthyes	()
subclass	Sarcopterygii	()
subclass	Dipnotetrapodomorpha	(Nelson 2006)
subclass	Tetrapodomorpha	()
—	Tetrapoda
—	Reptiliomorpha

Rank	Name	Author
—	Anthracosauria
subclass	Amphibiosauria	Kuhn 1967
—	Cotylosauria	()
—	Amniota
—	Sauropsida
class	Reptilia
—	Testudinata	(Oppel 1811)
order	Testudines	Batsch 1788
suborder	Cryptodira
family	Trionychidae	Gray 1825
subfamily	Trionychinae	Gray 1825
genus	Axestemys
species	splendidus	()

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.

†Axestemys splendidus Hay 1908

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Invalid names: Aspideretes granifer Hay 1909 [synonym], Aspideretes planus Parks 1933 [synonym]

Diagnosis

Reference	Diagnosis
N. S. Vitek 2012	Characters that help differentiate Axestemys splendida from other fossil trionychids but are not unique to this taxon include presence of a preneural, a single lateral hyoplastral process, and a maximum known carapace length at least 690 mm. Other characters taken from Gardner et al. (1995, p. 636) include “dorsomedian carapacial sculpture of larger individuals consists of high, narrow ridges bordering wavy, flat-bottomed, reticulate lacunae and (or) inosculating troughs; hypoplastral inguinal border thick; medial edge of xiphiplastral callosities in broad, unsutured medial contact in adults. Further differs from Aspideretoides foveatus as follows: length of epiplastral projections about one-quarter maximum hypoplastral width; epiplastral anterior projection wider and not tapered anteriorly; entoplastron gracile; skull wide, with broadly triangular face and blunt snout in dorsal view; face deep in lateral view; anterior edge of prefrontals shallowly emarginated laterally;...angle between anterior face of dentary symphysis and dorsal edge of labial ridge 30-40 degrees; dentary pockets broad and deep. Further differs from A. [Aspideretoides] allani in retaining sculpted plastral callosities and unfused hyoplastron and hypoplastron.” Unlike Campanian specimens described by Gardner et al. (1995), Maastrichtian specimens of Axestemys splendida may have a smooth, unsculpted skull roof.

Measurements

No measurements are available

Composition:

phosphaticsubp

Body part:

carapacef

Adult length:

100 to < 1000f

Grouping:

solitaryf

Environment:

brackish, freshwaterf

Locomotion:

actively mobilef

Life habit:

aquaticf

Diet:

piscivoref

Diet 2:

carnivoref

Reproduction:

oviparousf

Created:

2005-08-25 13:24:04

Modified:

2005-09-09 19:45:41

Source: f = family, subp = subphylum

References: Ernst and Barbour 1989, Carroll 1988

Age range: base of the Late/Upper Campanian to the top of the Late/Upper Maastrichtian or 83.50000 to 66.00000 Ma

Collections (9 total)

Time interval	Ma	Country or state	Original ID and collection number
Campanian	83.6 - 72.1	Canada (Alberta)	Aspideretes planus (177141) Aspideretoides splendidus (177024 177029)
Late/Upper Campanian	83.5 - 70.6	Canada (Alberta)	Aspideretoides splendidus (86515)
Middle Campanian - Late/Upper Campanian	83.5 - 70.6	USA (Montana)	Aspideretes granifer (177030) Aspideretoides splendidus (50827 177026 177027)
Late/Upper Maastrichtian	70.6 - 66.0	USA (South Dakota)	Axestemys splendida (174241)