Masrasector cf. ligabuei Crochet, Thomas, Roger, Sen, and Al-Sulaimani, 1990
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publication ID |
https://doi.org/ 10.26879/598 |
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persistent identifier |
https://treatment.plazi.org/id/FE3F87A4-FFF4-DC22-EB15-8510FE7AF948 |
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treatment provided by |
Felipe |
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scientific name |
Masrasector cf. ligabuei Crochet, Thomas, Roger, Sen, and Al-Sulaimani, 1990 |
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Masrasector cf. ligabuei Crochet, Thomas, Roger, Sen, and Al-Sulaimani, 1990
Figure 7 View FIGURE 7
Referred specimens. UON 84-360, right M1or2; UON 84-361, right M3; UON 84-397, right p3.
Measurements. UON 84-360, L> 3.57 mm, W> 5.55 mm; UON 84-361, L> 2.73 mm, W> 5.37 mm; UON 84-397, L = 5.1 mm; l = 2.7 mm.
Description. UON 84-360 is characterized by the presence of the metacone and paracone that are separated at mid-height ( Figure 7.1-2 View FIGURE 7 ). The base of the metacone is larger than that of the paracone. The parastyle and metastyle areas are unfortunately broken. The protofossa is large but heavily worn. The metaconule and paraconule cannot be distinguished but were surely present based on the size of the protofossa and the height of the preprotocrista and postprotocrista. The protocone is prominent. No cingulum is visible. It is currently impossible to determine whether UON 84-360 corresponds to a M1 or a M2.
UON 84-361 is only a protofossa ( Figure 7.3- 4 View FIGURE 7 ). Its transversal elongation and mesiodistal compression allow considering it as a fragment of M3. The protocone is well-developed. The paraconule and metaconule are well-defined; the former is the larger. There is a large precingulum along the protofossa.
UON 84-397 is a lower premolar ( Figure 7.5- 7 View FIGURE 7 ) that was probably blunt, as the condition observed in Masrasector species ( Peigné et al., 2007; Lewis and Morlo, 2010). Its protoconid is wide but heavily worn. There is no appreciable development of a paraconid, but the presence of a lingual precingulid could indicate the presence of a small paraconid. The area of the talonid is characterized by the presence of a postcingulid in both labial and lingual views. The absence of a wide postfossid, characterized by the presence of an entoconid, implies that the specimen better corresponds to a p3; the large size of the talonid excludes a p2 position.
Discussion. The well-marked separation of the paracone and metacone on UON 84-360 (M1or2) and the large size of the protofossa suggest that this specimen is better referred to the Teratodontinae rather than to the Hyainailourinae . The presence of the precingulum on UON 84-361 (M3) supports an attribution to the teratodontines for this specimen. Although this specimen is worn, the UON 84-397 premolar (p3) is clearly similar to those of the Masrasector species from the Fayum (Jebel Qatrani Fm., L-41, Priabonian; Jebel Qatrani Fm., Quarries A, E, G, I, M, Rupelian; Holroyd, 1994) notably because the surface of wear is flat and horizontal, as it is observed in Masrasector aegypticum (Jebel Qatrani Fm., Quarry G, Rupelian) ( Simons and Gingerich, 1974) . The upper molars are also morphologically similar to the molars known for Masrasector ( Crochet et al., 1990; Holroyd, 1994). Finally, the relative large size of p3 with respect to the upper molar size agrees with the attribution of this material to Masrasector .
The three specimens thus support the presence of a teratodontine ( Masrasector ) in the Algerian locality of Bir el Ater. The sizes of the specimens – notably the p3, which is the most complete tooth – agree with that of the specimens of Masrasector ligabuei , the medium-sized species of the genus among the Fayum fauna (Jebel Qatrani Fm., Quarries A, E, Rupelian) ( Holroyd, 1994, tables 5.1 and 5.2). We refer the three specimens from Bir el Ater as Masrasector cf. ligabuei , pending the discovery of better preserved material. Despite this lack of clear specific attribution, it is important to note that the specimens from Bir el Ater are the oldest to be known for the teratodontine genus Masrasector .
The oldest teratodontine so far known is Glibzegdouia tabelbalaensis from the Gour Lazib area ( Solé et al., 2014b). UON 84-360 molar is however not larger than the fragmentary M2 (HGL 10-15; L = 6.93 mm) recently described from the older locality of the Gour Lazib and attributed to G. tabelbalaensis ( Solé et al., 2014b) . Unfortunately, it is impossible to compare the morphology of the two specimens because HGL 10-15 corresponds only to a labial fragment.
Age and locality. Latest Bartonian or earliest Priabonian; Bir el Ater ( Algeria).
Teratodontinae indet.
Figure 8 View FIGURE 8
Referred specimen. CBI-1-614, right P4.
Measurements. L = 3.56 mm; W = 3.92 mm.
Description. CBI-1-614 is identified as a P4 because of the presence of a large protocone. The latter is bulbous and as long as the paracone. The paracone is elongated mesiodistally. The parastyle and metastyle are poorly developed and low; the metastyle is however slightly more developed than the parastyle. A centrocrista was possibly present. No cingulum is visible.
Discussion. CBI-1-614 recalls the P4 of Metasinopa napaki Savage, 1965 , Anasinopa leaki Savage, 1965 and Teratodon spekei Savage, 1965 , as well as that of the “proviverrines” – referred as Teratodontinae sensu Solé et al. (2014b) – described by Holroyd in her Ph.D. Thesis (1994). This is particularly shown in the presence of a large protocone and a poorly developed parastyle – and possible presence of a centrocrista. These features distinguish the P4 of the teratodontines from that of the contemporaneous hyainailourines. Indeed, the protocone is small and the metastyle is larger on the P4 of the latter.
We estimated the measurements expected for the P4 of Glibzegdouia tabelbalaensis based on a comparison with the P4 and m1 of Anasinopa leaki and m1 of Glibzegdouia tabelbalaensis : its length should be 7.2 mm, while the expected width should be 6.7 mm. As such, CBI-1-614 appears to be twice as small as the P4 expected for the sole teratodontine known at that time.
This discovery implies that the teratodontines were possibly diversified in the late Ypresian (or early Lutetian) of North Africa. This is similar to what is known for the hyainailourines (see above) ( Table 1).
The Namibian upper molar (BC 2’08) recently described by Pickford et al. (2008) as a Proviverrinae genus and species indet. – considered as a teratodontine by Solé et al. (2014b) – is one of the smallest hyaenodont ever recorded in Africa ( Pickford et al., 2008). However, the specimen is markedly smaller (L= 2.97 mm; W= 2.33 mm) than CBI- 1-614, supporting as well a diversity of the teratodontines during the late Ypresian-early Lutetian.
Age and locality. Late Ypresian or early Lutetian; Chambi CBI-1 ( Tunisia).
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