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Tetragonostylops apthomasi
Taxonomy
Trigonostylops apthomasi was named by Price and Paula Couto (1950). Its type specimen is DGM 154-M, a tooth (Right m1), and it is a 3D body fossil. Its type locality is São José de Itaborai, which is in an Eocene fissure fill marl in the Itaboraí Formation of Brazil. It is the type species of Tetragonostylops.
It was recombined as Tetragonostylops apthomasi by Paula Couto (1963).
It was recombined as Tetragonostylops apthomasi by Paula Couto (1963).
Synonymy list
| Year | Name and author |
|---|---|
| 1950 | Trigonostylops apthomasi Price and Paula Couto |
| 1963 | Tetragonostylops apthomasi Paula Couto |
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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.
†Tetragonostylops apthomasi Price and Paula Couto 1950
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| C. Paula Couto 1963 | As Trigonostylops but M1-2 tetragonal with protocone, paracone, and metacone well developed, the paracone higher, protocone and metacone subequal, hypocone strong, conical and isolated, lower than protocone, and immediately posterior to it, with a deep notch between them. Metaconule minute, commonly isolated, sometimes developed in low and short transverse crest connected to the basis of metacone. M3 without hypocone or with very weak or vestigial one, and trigon basin broad, more or less frankly open to the strong posterior cingulum, its round bottom bending posteriorly. P1-4 present, simpler than molars. P1 contiguous to C1, separated from P2 by short diastema. P2-4 contiguous. P2 and probably P1 much longer than wide, transversely compressed, with high mesial and somewhat conical and posteiorly shearing cusp; minute, posterior, basal cuspule sometimes present. P3-4 trigonal, P4 wider than long, anteroposteriorly compressed. P1-4 present, relatively well developed, small; P1 very small, with subconical mesial cusp, somewhat shearing anteroposteriorly. Diastema between P1-2 much shorter than in Trigonostylops. P2 smaller than the following teetg, similar to P1 but generally with very short talanoid, with a small, basal, posterior cuspule. P3 morphologically intermediate between P2 and P4, with vestigial metaconid on its lingual end; short talonid with small basal cuspule is present. P4 larger than P1-3, and somewhat molariform, with well developed trigonid crest, the lingual end of what bearing strong metaconid posterointernal to the protoconid and wide apart from it; talonid with very low and anteroposteriorly expanded hypoconid. Lower molars as in Trigonostylops, but trigonid much more anteroposteriorly expanded, with paraconid (?) very low, anteriomesial, a short and strongly inclined crest rising from it to the strong protoconid. Large preobital foramen over P2. Temporal crests strongly divergent from the conspicuous sagittal crest, almost transverse to it, and slightly concave posteriorly. Mandibular symphisis higher and much shorter than in Trigonostylops, transversely compressed, with somewhat concave external faces, and anteroinferior surface plane and wide transversely, and convex longitudinally, meeting the lateral faces at a straight angle. Angular lower flange or the symphisis, between anteroinferior surface and the lateral faces, somewhat salient, forming obtuse longitudinal crest, directed externally. |
Measurements
No measurements are available
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| Source: o = order, subc = subclass, c = class, subp = subphylum | |||||
| References: Lillegraven 1979, Carroll 1988, Ji et al. 2002, MacFadden et al. 1996, Hendy et al. 2009 | |||||
Age range: base of the Early/Lower Eocene to the top of the Lutetian or 55.80000 to 41.30000 Ma
Collections (2 total)
| Time interval | Ma | Country or state | Original ID and collection number |
|---|---|---|---|
| Early/Lower Eocene | Brazil (Rio de Janeiro) | Trigonostylops apthomasi, Trigonostylops sp. (type locality: 118314) | |
| Lutetian | Argentina (Chubut) | Tetragonostylops apthomasi (176170) |