PBDB Taxon

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Morphology	Ecology and taphonomy	External Literature Search	Age range and collections

Mesotherium cristatum

Osteichthyes - Notoungulata - Mesotheriidae

Taxonomy

Mesotherium cristatum was named by Serres (1857). It is not extant.

It was recombined as Typotherium cristatum by Serres (1857), Ameghino (1887), Ameghino (1887), Lydekker (1894); it was synonymized subjectively with Mesotherium maendrum by Cabrera (1937).

Synonyms

Typotherium pachygnatum was named by Gervais and Ameghino (1880). It is not extant.

It was synonymized subjectively with Mesotherium cristatum by Fernández-Monescillo et al. (2023).
Typotherium maendrum was named by Ameghino (1887). It is not extant.

It was synonymized subjectively with Typotherium cristatum by Mercerat (1891).
Typotherium exiguum was named by Ameghino (1887). It is not extant.

It was synonymized subjectively with Typotherium eguiai by Ameghino (1904); it was synonymized objectively with Mesotherium cristatum by Fernández-Monescillo et al. (2023).
Typotherium eguiai was named by Ameghino (1904).

It was synonymized subjectively with Typotheridion maendrum by Cabrera (1939); it was synonymized objectively with Mesotherium cristatum by Fernández-Monescillo (2018).
Entelomorphus rotundatus was named by Ameghino (1889).

It was synonymized objectively with Mesotherium cristatum by Fernández-Monescillo (2018).
Mesotherium angustirostrum was named by Cattoi (1941).

It was synonymized objectively with Mesotherium cristatum by Fernández-Monescillo et al. (2023).
Mesotherium maendrum was named by Ameghino (1887).

It was recombined as Typotheridion maendrum by Cabrera (1939); it was synonymized subjectively with Mesotherium cristatum by Fernández-Monescillo et al. (2023).
Typotherium angustirostrum was named by Cattoi (1941).

It was synonymized subjectively with Mesotherium cristatum by Fernández-Monescillo et al. (2023).
Bravardia pampeana was named by Cattoi (1941). Its type specimen is MACN A 2037, a maxilla (DP2, DP3, P4-M3), and it is a 3D body fossil.

It was synonymized objectively with Mesotherium cristatum by Fernández-Monescillo (2018).
Pseudotypotherium maendrum was named by Ameghino (1887).

It was synonymized objectively with Mesotherium cristatum by Fernández-Monescillo et al. (2023).

Synonymy list

Year	Name and author
1857	Mesotherium cristatum Serres p. 961
1857	Typotherium cristatum Serres p. 961
1880	Typotherium pachygnatum Gervais and Ameghino p. 90
1887	Mesotherium maendrum Ameghino
1887	Pseudotypotherium maendrum Ameghino
1887	Typotherium maendrum Ameghino p. 10
1887	Typotherium exiguum Ameghino p. 11
1887	Typotherium cristatum Ameghino p. 49
1887	Typotherium pachygnatum Ameghino p. 50
1889	Entelomorphus rotundatus Ameghino p. 421
1894	Typotherium cristatum Lydekker p. 10
1904	Typotherium eguiai Ameghino p. 27
1914	Typotherium maendrum Rovereto p. 118
1914	Typotherium exiguum Rovereto p. 121
1939	Typotheridion maendrum Cabrera
1941	Bravardia pampeana Cattoi
1941	Mesotherium angustirostrum Cattoi
1941	Typotherium angustirostrum Cattoi
1965	Mesotherium maendrum Francis
2023	Mesotherium cristatum Fernández-Monescillo et al.

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Rank	Name	Author
kingdom	Animalia	()
—	Bilateria
—	Eubilateria	Ax 1987
—	Deuterostomia
phylum	Chordata	Haeckel 1874
subphylum	Vertebrata
superclass	Gnathostomata
class	Osteichthyes
subclass	Sarcopterygii	()
subclass	Dipnotetrapodomorpha	(Nelson 2006)
subclass	Tetrapodomorpha	()
—	Tetrapoda
—	Reptiliomorpha
—	Anthracosauria
subclass	Amphibiosauria	Kuhn 1967
—	Cotylosauria	()
—	Amniota
subclass	Synapsida
—	Therapsida	()
infraorder	Cynodontia	()

Rank	Name	Author
—	Mammaliamorpha
—	Mammaliaformes
class	Mammalia
—	Cladotheria
—	Zatheria
subclass	Tribosphenida	()
subclass	Theria
—	Eutheria	()
—	Placentalia
superorder	Afrotheria
—	Paenungulatomorpha
superorder	Paenungulata
—	Sudamericungulata
order	Notoungulata
suborder	Typotheria	Zittel 1892
family	Mesotheriidae	Alston 1876
subfamily	Mesotheriinae	Alston 1876
tribe	Pampaini
genus	Mesotherium	Serres 1867
species	cristatum	Serres 1857

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.

†Mesotherium cristatum Serres 1857

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Invalid names: Bravardia pampeana Cattoi 1941 [objective synonym], Entelomorphus rotundatus Ameghino 1889 [objective synonym], Mesotherium angustirostrum Cattoi 1941 [objective synonym], Mesotherium maendrum Ameghino 1887 [synonym], Pseudotypotherium maendrum Ameghino 1887 [objective synonym], Typotherium angustirostrum Cattoi 1941 [synonym], Typotherium eguiai Ameghino 1904 [objective synonym], Typotherium exiguum Ameghino 1887 [objective synonym], Typotherium maendrum Ameghino 1887 [synonym], Typotherium pachygnatum Gervais and Ameghino 1880 [synonym]

Diagnosis

Reference	Diagnosis
M. Fernández-Monescillo et al. 2023	Suborbital fossa absent; small infraorbital foramen; permanent dental formula 1-0-2-3/2-0-1-3; incisive foramen heart-shaped with broad distal/caudal intrusion, sometimes extending beyond the transverse premaxilla-maxilla suture; ventral border of zygo- matic arch rounded or with variable caudoventral angulation; epitympanic theca with inflated dorsolateral border; tympanic bulla flat or slightly inflated laterally with marked styliform process ventro-rostrally oriented; I1 strongly mesiodistally elon- gate with broad, shallow lingual fold; striation on labial face of I1; P3 lingual side concave or simple with slight enamel fold; P4 lingually bilobed (simple enamel fold, mesiolaterally oriented); M1-M3 with undulating ectolophs; general ectoloph outline of M1-M2 concave to flat; ectoloph of M3 concave with laterally displaced parastyle; i1 subrectangular (similar longitudinal width); i1 distal border concave; i1 striations on labial border varying from slight to marked; ratio length of i1 with i2 c. 5/1; ventral border of the symphysis slightly convex or flat; dorsal border of the lower diastema (between i2 and p3) with a robust dorsal crest. The features exclusive to this taxon are I1 strongly mesiodistally elongated, absence of suborbital fossa and small infraorbital foramen.