Morotodon aenigmaticus gen. et, 2022

Crespo, Vicente D., Goin, Francisco J. & Pickford, Martin, 2022, The last African metatherian, Fossil Record 25 (1), pp. 173-186 : 173

Morotodon aenigmaticus gen. et sp. nov.

Etymology.

"The mysterious tooth from Moroto". Moroto II is the fossil locality where this taxon was found; “-odon”, from odontos, genitive of odous, ancient Greek for tooth; gender is masculine; Morotodon aenigmaticus , from the Latin aenigma (mystery), refers to the unexpected finding of a metatherian near the Equator in the Neogene of Africa.

Holotype.

UM MOR II, 48'04, a last lower left molar (m4; Figs 2 , 3 ; Suppl. material 1 and Suppl. material 2).

Measurements.

Total length, 1.63 mm (1 mm trigonid length, 0.63 talonid length); trigonid width, 0.93 mm; talonid width, 0.94 mm (from Pickford and Mein 2006).

Locality and age.

Moroto II, north of Nakiloro Village, Moroto District, northeastern Uganda (Fig. 1 ). Late early Miocene, upper Burdigalian (16.5-15.5 Ma).

Diagnosis.

?Herpetotherid metatherian with lower molars having a short anterior cingulid, a buccal shelf, and a trigonid and talonid with subequal length and width; the m4 has a vertical, well-developed hypoconulid in a central position. The specific diagnosis extends to the genus by monotypy.

Description.

Specimen UM MOR II, 48'04 is bi-rooted, both roots being subcircular in section; the anterior root is smaller than the posterior one. The anterior cingulid is short and relatively wide at its central portion. The trigonid is open. The main cusps of the trigonid are well-developed. The paraconid is mesio-lingually positioned. The protoconid is the largest cusp of the tooth, and is slightly anteriorly placed with respect to the metaconid. The paracristid and metacristid are notched. The talonid is bucco-lingually compressed in its anterior half; at its posterior face its width is almost the same as that of the trigonid. The entoconid is broken; apparently, it was bucco-lingually compressed; the pre-entocristid is straight and ends in at posterolingual edge of the metaconid. The hypoconulid is separated from the entoconid; it is well-developed and is centrally placed on the posterior edge of the tooth; it is a vertical cusp (i.e., it is not posteriorly oriented or dorso-ventrally compressed). The hypoconid is only moderately developed; it is also buccally salient, but does not exceed buccally the level of the protoconid. The oblique cristid joins the posterior wall of the trigonid at the labiolingual midpoint of the tooth, below the metacristid notch. There is a well-developed buccal shelf, or cingulid, at the base of the crown, running from the base of the hypoconid to the posterobuccal edge of the protoconid. The tooth shows soil corrosion.

Comments.

The specimen was originally described as a m1 or m2 ( Pickford and Mein 2006). The reduced (laterally compressed) talonid at its anterior half, only moderately developed hypoconid, relatively central position of the hypoconulid, as well as the quite oblique orientation of the oblique cristid, allow us to reassign the specimen to an m4. This kind of reduction in the m4's talonid appears in several metatherians (e.g., Peradectes russelli Crochet, 1979 or Amphiperatherium giselense (Heller, 1936)).

Comparisons.

Specimen UM MOR II, 48'04 is clearly not a deciduous tooth, due to the size and shape of its roots and the angle at which they would be inserted into the mandible. Several eutherian lineages have molar morphologies that are superficially similar to that of Morotodon aenigmaticus : afrosoricid “insectivores” (Afrotheria), bats ( Chiroptera ), some eulipothyplans (Laurasiatheria, Eulipotyphla ), and adapisoriculids (Euarchonta). Early afrotherians include Ocepeia , from the late Paleocene of Morocco, which is strikingly different from Morotodon . Ocepeia has bunoid, almost inflated lower molars with low protoconid, paraconid close to the metaconid; enclosed, deep trigonid basin; the metacristid is not vertical but gently sloping; talonids are multicuspid (up to five cusps), with a reduced hypoconulid. Among the Afroinsectiphilia, macroscelidians can also be discarded: for instance, the middle-late Eocene Nementchatherium has very low cusps, the paraconid is close to the protoconid and the hypoconulid, if present, is almost indistinguishable. Chambius , from the early or early middle Eocene of Tunisia, has its lower molars rounded in profile, with an indistinguishable hypoconulid, indistinct paraconid, and the talonid narrower than the trigonid.

Afrosoricids such as tenrecs and golden moles (of which at least members of the former were contemporaneous with Morotodon ), were already discarded on the basis of the number of talonid cusps, three in metatherians and a single, elongated one in tenrecs ( Pickford and Mein 2006). Effectively, tenrecids such as Promicrogale , from the Miocene of Namibia ( Pickford 2018) or Nanogale from the Eocene of Namibia ( Pickford 2019), have quite different lower molars in which the talonid is much smaller than the trigonid and lacks a hypoconulid, the paraconid in m2-3 is low and close to the metaconid, and the protoconid is proportionally very large; the talonid basin is much lower than that of the trigonid. Chrysochlorids have highly derived molars, of which the lower ones lack the talonid, while the paraconid and metaconid are reduced and twinned.

Chiropterans can also be ruled out because of the morphology and position of the hypoconulid, which in Morotodon is more developed and more centrally placed at the distal edge of the tooth; additionally, chiropterans have a buccal shelf or cingulid which is mesiodistally complete, linking the anterior and posterior cingulids. Morotodon differs from the probable chiropteran Ghamidtherium dimaiensis Sánchez-Villagra, Seiffert, Martin, Simons, Gunnell, & Attia, 2007 in that the anterior cingulid is shorter and does not extend distally at the crown base; the metaconid is anteriorly positioned with respect of the protoconid; the entoconid is less developed; it lacks a posterior cingulid; the hypoconulid is larger, higher and less dorso-ventrally compressed, and it is not placed immediately distal to the entoconid but instead buccal to it; finally, the oblique cristid in Morotodon is less parallel to the dental axis.

Morotodon differs from the Eulipotyphla in the presence and morphology of the hypoconulid. In their lower molar morphology representatives of the Soricidae and Talpidae have some similarities with Morotodon . However, the anterior cingulid in soricids is better developed and may continue posteriorly towards the buccal surface of the crown, and in the talonids the hypoconulid is reduced (or, if not reduced, is placed very low regarding the entoconid) and located immediately posterior to the entoconid. Generalized erinaceids such as Galerix lack a hypoconulid, and, in the last molar, the paraconid is crest-like, and the oblique cristid is parallel to the dental axis. Among other more derived soricomorphs, the living Solenodon , for instance, has extremely reduced talonids and mesio-distally compressed trigonids.

Being more similar in overall morphology (but see below), a more detailed comparison of Morotodon with individual adapisoriculid taxa is worthwhile. Morotodon differs from Afrodon gheerbranti De Bast & Smith, 2017 in having a more lingual paraconid, more developed protoconid, presence of a buccal shelf (or cingulid), better developed hypoconid and entoconid, and a more centrally placed hypoconulid. It differs from Afrodon chleuhi Gheerbrant, 1988 in having a longer trigonid, a better developed protoconid, trigonid and talonid of similar width, and a less developed, more anteriorly placed hypoconulid. It differs from Bustylus marandati (Crochet and Sigé 1983) in having a narrower anterior cingulum, longer trigonid, more centrally placed metaconid, a developed buccal shelf, a larger entoconid, and an independent hypoconulid. It differs from the todralestid Todralestes variabilis Gheerbrant, 1991 in having a less reduced talonid, the presence of a buccal shelf, and a larger hypoconulid.

Comparisons with early Marsupialiformes .

Morotodon aenigmaticus compares best with metatherian mammals, especially with Marsupialiformes (most metatherians except the early clade Deltatheridia). The best known early marsupialiform (i.e., non deltatheroid) metatherian is Kokopellia juddi Cifelli, 1993, from the medial Cretaceous of Utah in North America (see Cifelli and Muizon 1997 for a detailed description of the dentition of Kokopellia ). Molars of Kokopellia represent the generalized condition for almost all Cenozoic metatherians. Morotodon aenigmaticus differs from Kokopellia juddi in that its m4 lacks a posterior cingulid, and a shorter talonid (clearly longer in Kokopellia in all lower molars), a less posteriorly placed metaconid, a smaller hypoconulid (in Kokopellia it is larger and closer to the entoconid), and a smaller and less anteriorly placed hypoconid. Both Morotodon and Kokopellia share a well-developed buccal shelf (or cingulid), and a similarly oriented oblique cristid, which ends anteriorly at a point below the metacristid notch.

Comparisons with Peradectidae .

Most Cenozoic Holarctic metatherians belong either to the Peradectidae or to the Herpetotheriidae , so a detailed comparison with species of these two groups is needed in order to clarify the affinities of Morotodon aenigmaticus . Most representatives of both families are known from the Northern Hemisphere. In North America, peradectids and herpetotheriids are known from the Late Cretaceous to the Miocene, while in Eurasia they span the early Eocene to the Miocene (in Europe, peradectids are restricted to the Eocene). In Africa, peradectids had been known only for the early Eocene ( Kasserinotherium ),.while herpetotheriids are known for the early Oligocene ( Peratherium ). Our allocation of Morotodon to herpetotheriids expands the group to the Miocene.

Peradectes . Morotodon aenigmaticus differs from Peradectes louisi Crochet, 1979 in having a proportionally longer talonid, less difference in height between the trigonid and the talonid, and in that the hypoconid is more salient. Differs from Peradectes californicus (Stock, 1936) (m4 of this species is unknown) in that the metaconid is more anteriorly placed than the protoconid, and the talonid is proportionally narrower. Differs from Peradectes chesteri Gazin, 1952 (although the m4 of this species is unknown) in having a larger paraconid which is not as close to the metaconid, and a proportionally larger hypoconulid. Differs from Peradectes coprexeches Williamson & Taylor, 2011 in having a narrower trigonid, the oblique cristid is not subparallel to the preentocristid (in such a way that the talonid is anteriorly narrower), the hypoconulid is more developed and less paired to the entoconid; finally, a buccal cingulid is present. Differs from Peradectes minor Clemens, 2006 and Peradectes mutigniensis Crochet, 1979 in having a paracristid which is less transverse to the dental axis, the hypoconulid is farther from the entoconid, it lacks a posterior cingulid and has a buccal shelf or cingulid. Differs from Peradectes pauli (Gazin, 1956) in having a more salient hypoconid, while the oblique cristid is less parallel to the dental axis. Differs from Peradectes protinnominatus McKenna, 1960 in having a longer talonid, a larger hypoconulid which is farther from the entoconid, and in that the oblique cristid is less parallel to the dental axis. Differs from Peradectes russelli Crochet, 1979 in that the paraconid and metaconid are less close to each other, the entoconid is smaller, the hypoconulid is farther from the entoconid, and the oblique cristid is less parallel to the dental axis.

Mimoperadectes . Differs from Mimoperadectes labrus Bown & Rose, 1979 in having a less developed anterior cingulid, a shorter trigonid, a paraconid that is farther from the metaconid and the hypoconulid and the entoconid are more detached (for this reason, the talonid is wider posteriorly).

Nanodelphys . Differs from Nanodelphys hunti (Cope, 1873) in having a narrower trigonid and shorter talonid, a hypoconulid that is set farther from the entoconid, and the oblique cristid not being subparallel to the preentocristid.

Armintodelphys . Differs from Armintodelphys dufraigni Smith & Smith, 2013 in having a wider anterior cingulid, a less reduced paraconid, a slightly posteriorly placed paraconid (relative to the protoconid), a less straight oblique cristid, a hypoconulid that is farther from the entoconid, and in the presence of a buccal shelf. Differs from Armintodelphys dawsoni Krishtalka & Stucky, 1983 in having a more developed paraconid which is less mesio-distally compressed, and a narrower talonid. Differs from Armintodelphys blacki Krishtalka & Stucky, 1983 in having an anteriorly placed metaconid with respect to the protoconid, the anterior half of the oblique cristid not being parallel to the dental axis, a smaller hypoconulid that is farther from the entoconid, and a narrower talonid basin.

Comparisons with Herpetotheriidae .

Asiadidelphis . Morotodon aenigmaticus differs from Asiadidelphis zaissanense Gabunia, Shevyreva, & Gabunia, 1990 (described in Ziegler et al. 2007; fig. 3.3) in having a wider anterior cingulid, oblique cristid less parallel to the dental axis, and a more buccally placed hypoconulid. Differs from Asiadidelphis tjutkovae Emry, Lucas, Szalay, & Tleuberdina, 1995 in its smaller size, a more centrally positioned hypoconulid on the posterior edge of the talonid, and a larger entoconid. Differs from Asiadidelphis (= Indodelphis ) luoi (Bajpai, Kapur, Thewissen, Tiwari, & Das, 2005) in having a more developed anterior cingulid, a proportionally higher protoconid relative to the metaconid, a mesio-distally less compressed paraconid, a narrower talonid an oblique cristid that is less parallel to the dental axis.

Swaindelphys . Differs from Swaindelphys encinensis Williamson & Taylor, 2011 in having a shorter anterior cingulid, narrower trigonid and talonid, a less developed, lower hypoconulid, and, in occlusal view, a straight but not curved oblique cristid. Differs from Swaindelphys cifelli Johanson, 1996 in having a more developed anterior cingulid, in its hypoconulid which is farther from the entoconid, a smaller hypoconulid, and a talonid that is longer relative to the trigonid.

Thylacodon . Differs from Thylacodon montanensis Williamson, Brusatte, Carr, Weil, & Standhardt, 2012 in having (although the m4 was not preserved in the latter) a narrower entoconid, a hypoconulid that is farther from the entoconid, and in the absence of a posterior cingulid. Differs from Thylacodon pusillus (Archibald, 1982) in having a better developed anterior cingulid, smaller entoconid, and a hypoconulid that is not twinned to the entoconid.

Golerdelphys . Differs from Golerdelphys stocki Williamson & Lofgren, 2014 in lacking a posterior cingulid and in that the entoconid is proportionally smaller.

Copedelphys . Differs from Copedelphys titanelix (Matthew, 1903) in having a shorter and wider anterior cingulid, a proportionally smaller trigonid, a paraconid that is not mesio-distally compressed, an oblique cristid obliqua is not straight, a buccally more salient hypoconid, and in that the hypoconulid is less posteriorly projected. Differs from Copedelphys stevensoni (Cope, 1873) in having a shorter and wider anterior cingulid, a less antero-posteriorly compressed paraconid, an oblique cristid obliqua that is less parallel to the preentocristid, and in the presence of a buccal shelf (or cingulid).

Herpetotherium . Differs from Herpetotherium youngi (McGrew, 1937) in having a shorter anterior cingulid, an oblique cristid that meets the trigonid more lingually, a more developed hypoconulid that is not twinned to the entoconid, and a more salient hypocone. Differs from Herpetotherium fugax Cope, 1873 in having a shorter and wider anterior cingulid, a proportionally narrower trigonid, a paracristid that is less transversal to the dental axis, an oblique cristid that is not subparallel to the preentocristid, and a hypoconulid that is farther from the entoconid. Differs from Herpetotherium comstocki (Cope, 1884) in having a shorter anterior cingulid, an oblique cristid that is subparallel to the dental axis, a proportionally larger hypoconulid that is farther from the entoconid; in turn, this last cusp is proportionally smaller. Differs from Herpetotherium edwardi (Gazin, 1952) in having larger paraconid and hypoconulid, the latter smaller and farther from the entoconid, and an oblique cristid that is less parallel to the dental axis. Differs from Herpetotherium marsupium Troxell, 1923 in having a smaller entoconid, more buccal hypoconulid, and a straighter oblique cristid that is less parallel to the dental axis. Differs from Herpetotherium merriami (Stock & Furlong, 1922) in having (although the m4 was not preserved) a larger hypoconulid which is placed farther from the entoconid. Differs from Herpetotherium tabrumi Korth, 2018 in having (although the m4 is not present) a larger hypoconulid which is farther from the entoconid, a shorter preentocristid, and an oblique cristid that is less parallel to the dental axis. Differs from Herpetotherium valens (Lambe, 1908) in having (although the m4 was not preserved) a shorter and wider anterior cingulid, relatively narrower talonid, a paracristid that is less transversal to the dental axis, paraconid and metaconid clearly set apart from each other, a smaller entoconid and a proportionally larger hypoconulid that is farther from the entoconid.

Peratherium (Fig. 3 ). Differs from Peratherium africanum in having a shorter and wider anterior cingulid, deeper oblique cristid which is less parallel to the dental axis, a slightly sloping and not vertical posterior wall of the trigonid (the metacristid), and a more buccally placed hypoconulid. Differs from Peratherium bretouense Crochet, 1979 in having a shorter anterior cingulid, a less developed entoconid, a less bucco-lingually compressed hypoconulid that is placed farther from the entoconid, and lack of a posterior cingulid. Differs from Peratherium cayluxi Filhol, 1877 in having a shorter anterior cingulid, a more buccally salient hypoconid, and a smaller entoconid. Differs from Peratherium constans (Teilhard de Chardin, 1927) in having a wider and shorter anterior cingulid, a more buccally salient hypoconid, a smaller hypoconulid that is placed farther from the entoconid. Differs from Peratherium cuvieri (Fischer, 1829) in having (although the m4 was not preserved in the latter) a proportionally larger hypoconulid which is more buccally placed, lack of a posterior cingulid, a smaller entoconid, and a longer talonid. Differs from Peratherium elegans (Aymard, 1846) in having a narrower anterior cingulid, a larger hypocone which is less rounded, a larger and more buccally placed hypoconulid of which the buccal slope does not form a continuum with the posthypocristid. Differs from Peratherium lavergnense Crochet, 1979 in that the hypoconid is more buccally salient, the hypoconulid is larger and not placed immediately posterior to the entoconid. Differs from Peratherium matronense Crochet, 1979 in having a shorter anterior cingulid, a more anteriorly placed metaconid regarding the protoconid, and a hypoconulid that is not immediately distal to the entoconid. Differs from Peratherium monspeliense Crochet, 1979 in having a shorter anterior cingulid, and in that the oblique cristid is less parallel to the dental axis. Differs from Peratherium perrierense Crochet, 1979 in having a shorter anterior cingulid, an oblique cristid that is less parallel to the dental axis, and a hypoconulid that is farther from the entoconid. Differs from Peratherium sudrei Crochet, 1979 in that the hypoconulid is closer to the entoconid, and the entoconid and the hypoconid are at the same level (while in P. sudrei the entoconid is more anteriorly placed).

Amphiperatherium (Fig. 3 ). Differs from Amphiperatherium brabatense Crochet, 1979 in having a wider anterior cingulid, and a proportionally larger and more buccally placed hypoconulid. Differs from Amphiperatherium minutum (Aymard, 1846) in having a less reduced talonid and in that the hypoconid is more buccally salient. Differs from Amphiperatherium goethei Crochet, 1979 in having a shorter anterior cingulid, a paraconid that is less close to the metaconid (therefore, the trigonid is less mesiodistally compressed), and an anteriorly slightly narrower talonid. Differs from Amphiperatherium lamandini (Filhol, 1876) in having a more salient hypoconid, larger hypoconulid which is farther from the entoconid, and in lacking a posterior cingulid. Differs from Amphiperatherium frequens (Meyer, 1846) in having a less reduced talonid, a shorter anterior cingulid, presence of a buccal cingulid, and the hypoconulid that is farther from the entoconid. Differs from Amphiperatherium maximum Crochet, 1979 in its smaller size, shorter anterior cingulid, a mesio-distally less compressed paraconid, a larger hypoconulid that is placed farther from the entoconid, and a smaller entoconid. Differs from Amphiperatherium bastbergense Crochet, 1979 in having a shorter anterior cingulid, a mesio-distally less compressed paraconid, a smaller entoconid, a larger hypoconulid that is farther from the entoconid, and in the absence of a posterior cingulid. Differs from Amphiperatherium fontense Crochet, 1979 in having a smaller anterior cingulid, an anteriorly narrower talonid, a proportionally smaller entoconid, and a hypoconulid that is larger and placed farther from the entoconid. Differs from Amphiperatherium ambiguum (Filhol, 1877) in having a shorter anterior cingulid and the hypoconulid being farther from the entoconid. Differs from Amphiperatherium exile (Gervais, 1848-52) in having a shorter anterior cingulid, a mesio-distally less compressed paraconid and an anteriorly narrower talonid. Differs from Amphiperatherium bourdellense Crochet, 1979 in having a narrower talonid and a more central position of the hypoconulid, which is placed farther from the entoconid. Differs from Amphiperatherium giselense (Heller, 1936) in having a mesio-distally less compressed paraconid, larger hypoconulid, anteriorly narrower talonid, and lack of a posterior cingulid.

Rumiodon . Differs from Rumiodon inti Goin & Candela, 2004 in having a wider anterior cingulid, distinct hypoconulid that is larger and not twinned with the entoconid, and an oblique cristid that is less parallel to the dental axis.

Comparisons with other Cenozoic Holarctic metatherians.

Estelestes . Differs from Estelestes ensis Novacek, Ferrusquía-Villafranca, Flynn, Wyss, & Norell, 1991 (early Eocene; referred by the authors to the " Didelphidae "), in that it lacks a postcingulid (in Estelestes the postcingulid extends anteriorly forming a buccal cingulid basal to the hypocone), the hypocone is more buccally salient, the hypoconulid is farther from the entoconid and less posteriorly tilted; finally, an oblique cristid is less parallel to the dental axis.

Orhaniyeia . Differs from Orhaniyeia nauta Métais, Coster, Kappelman, Licht, Ocakoğlu, Taylor, & Beard, 2018 (middle Eocene of Turkey) in being much smaller, has less bunoid molars, the anterior cingulid is better developed, the paraconid is placed farther from the metaconid, the paracristid is less transverse to the dental axis, the talonid is shorter, the hypoconid is much more distally placed, an oblique cristid that is less parallel to the dental axis; finally, it lacks multiple cuspids on the pre-entocristid.

Comparisons with South American “opossum-like” metatherians.

Morotodon aenigmaticus differs from the Protodidelphidae (early to middle Eocene) in being much smaller, has less bunoid molars, and smaller and narrower talonids. Differs from the Derorhynchidae (Paleogene of South America and Antarctica) in having a longer talonid, no posterior cingulid, smaller entoconid and larger hypoconulid. Differs from species of Gaylordia (early Eocene) in having a less developed anterior cingulid, longer talonid, less lingually placed paraconid; finally, an oblique cristid that is less parallel to the dental axis. Differs from species of Marmosopsis (early Eocene) in lacking a posterior cingulid and an oblique cristid that is less subparallel to the dental axis. Differs from species of Minusculodelphis (Eocene) in its larger size, better developed talonids and hypoconid, and in the persistence of the hypoconulid. Differs from species of Monodelphopsis (early Eocene) in having a narrower talonid, an oblique cristid that is less subparallel to the dental axis, and better developed entoconid and hypoconulid which are less closely set to each other. Differs from species of Carolopaulacoutoia (early Eocene) in its shorter talonid, less parallel oblique cristid to the dental axis, more salient hypoconid, and smaller and more centrally placed hypoconulid. Differs from species of Itaiboraidelphys (early Eocene) in having a poorly developed anterior cingulid, the paraconid is more distant from the metaconid, an oblique cristid that is less parallel to the dental axis, and the hypoconulid is more centrally placed. Differs from species of Didelphopsis (Paleocene-early Eocene) in having a shorter anterior cingulid, proportionally longer trigonid, the paraconid is placed farther from the metaconid, an oblique cristid that is less parallel to the dental axis, and the hypoconulid is larger and farther from the encotonid. Differs from Pucadelphys andinus Marshall & Muizon, 1988 (early Paleocene) in having a larger hypoconulid and an oblique cristid that is less parallel to the dental axis.

Figures

Figure 1. Map of Africa indicating the occurrences of extinct metatherians, or taxa previously regarded as Metatheria. Bottom left, map of Uganda indicating the Moroto II locality. Right, geologic time column indicating the age of each taxon. References: E, Equator; 1,? Garatherium todrae; 2, Garatherium mahboubii; 3, Kasserinotherium tunisiense; 4, Ghamidtherium dimaiensis; 5, Peratherium africanum; 6, Morotodon aenigmaticus gen. et sp. nov. See the text and Table 1 for more information on these taxa.

Figure 2. Morotodon aenigmaticus gen. et sp. nov. SEM images of specimen UM MOR II, 48 ' 04 (an isolated left m 4) in occluso-labial (A) and occlusal (B) views. Scale bar: 1 mm.

Figure 3. Lower molar series of various marsupial taxa belonging to Peradectidae (A) and Herpetotheriidae (B-F). A. Peradectes russelli, CB 1027 (CL), right m 4 in lingual, occlusal, and labial views; B. Amphiperatherium lamandini, ECA 3104 (UM), fragment of right mandible with m 3 - 4 in occlusal view; C. Peratherium elegans (type of Peratherium agmardi Filhol), QU 8216 (MNHN), right mandible with c and p 1 - m 4 in occlusal view; D. Peratherium perrierense (holotype), PRR 2524, right mandible with i 1 - m 4 in occlusal view; E. Peratherium cayluxi, QU 8217 (MNHN) (holotype), left mandible with p 2 - m 1 and m 3 - 4 in occlusal view; F. Amphiperatherium ambiguum, PLA 1042 (UM), left m 4 in occlusal and lingual views. Figures after Crochet (1980). Scale bars: 1 mm.