CAVIOIDEA Fischer de Waldheim, 1817
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publication ID |
https://doi.org/ 10.26879/742 |
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publication LSID |
lsid:zoobank.org:pub:540D23AA-F705-4A05-8E10-FADAD3356D9C |
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persistent identifier |
https://treatment.plazi.org/id/03A587B4-E531-AC0C-FC8A-D5C8FF04167C |
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treatment provided by |
Felipe |
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scientific name |
CAVIOIDEA Fischer de Waldheim, 1817 |
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CAVIOIDEA Fischer de Waldheim, 1817 or CHINCHILLOIDEA Bennett, 1833 Gen. et sp. indet.
Figure 6.15 View FIGURE 6 -17, Appendix 3
2016 Eobranisamys sp. Antoine et al., Supplementary data, p. 9.
2016 Cachiyacuy cf. contamanensis Antoine et al. , Supplementary data, p. 9.
2016 Caviomorpha indet., sp. 1 Antoine et al., Supplementary data, p. 9.
2017 Eobranisamys sp. Antoine et al., Supplementary data, p. 9.
2017 Cachiyacuy cf. contamanensis Antoine et al. , Supplementary data, p. 9.
2017 Caviomorpha indet. sp. 1, Antoine et al., Supplementary data, p. 9.
Referred material. MUSM 2834, right dp4 ( Figure 6.16 View FIGURE 6 ); MUSM 2835, right m2 ( Figure 6.15 View FIGURE 6 ); MUSM 2836–2837, fragmentary right upper molars ( Figure 6.17 View FIGURE 6 ).
Locality. Contamana CTA-29, Loreto Department, Peru.
Formation and age. Pozo Formation, lower member, late middle Eocene ( Antoine et al., 2016).
Description. The dp4 (MUSM 2834; Figure 6.16 View FIGURE 6 ) is relatively larger compared to other dp4s found at CTA-29. This tooth is pristine and brachydont, with slender transverse cristids, and small but well-defined and acute mesostylid, entoconid, and hypoconid. The metaconid and protoconid are much more crestiform. This deciduous lower premolar is pentalophodont. Mesially, the metalophulid I, well-curved, connects to the protoconid labially and ends and the base of the metaconid lingually. The metaconid, mesiodistally pinched, is faintly linked to the crestiform protoconid via its posterior arm, which forms a quasi-complete metalophulid II. There is a minute enamel cuspid on the anteroflexid at the base of the distal wall of the metalophulid I. The metaconid does not develop a posterior arm. In the middle part of the tooth, the lingual margin bears a well-defined and isolated mesostylid. The mesial ectolophid is almost transverse and appears in continuity with a mesolophid, which extends lingually to the mesostylid. Labially, the mesial and sub-transverse ectolophid displays an enamel swelling, which could be interpreted as a neomesoconid-like cuspid. The distal ectolophid is small and very low. As such, the hypoflexid and distal mesoflexid are virtually confluent. In this context, the third transverse cristid has no link with the surrounding cristids, and the hypoflexid-distal mesoflexid and mesial mesoflexid are transversely open. The hypoconid is the largest cuspid of the tooth, labially opposed to the entoconid. Both cuspids are linked by a thin and sinuous hypolophid. The second transverse cristid, mesolophid, and hypolophid are parallel and slightly curved. The anterior arm of the hypoconid is faintly marked, lower and grooved, and it is weakly connected to the hypolophid (i.e., pseudo-taeniodont). Distolabially, the posterolophid faintly links the hypoconid, distolingually ending its course far from the entoconid. Thus, the broad metaflexid remains open lingually.
The m2 (MUSM 2835; Figure 6.15 View FIGURE 6 ) is corroded and damaged, with a dental structure still visible. This tetralophodont tooth is particularly large with a trigonid as wide as the talonid. Two enamel wrinkles are directed backwardly to the metalophulid I, and one directed forwardly to the second transverse cristid. Due to wear, it is difficult to tell if this second cristid was connected or not to the mesostylid. This cristid could be a complete metalophulid II or a composite cristid made by a labial short posterior arm of the protoconid associated with a short neomesolophid. The ectolophid is oblique and distally connected both to a short but strong anterior arm of the hypoconid (i.e., non-taeniodont pattern) and to the transverse and strong hypolophid. The posterolophid is lingually separate from the entoconid. The mesoflexid and posteroflexid are lingually open.
Both labial fragments (MUSM 2836 and 2837; Figure 6.17 View FIGURE 6 ) document large upper molars. The labial cusps are well-defined: parastyle, paracone, mesostyle, and metacone. MUSM 2836 is tetralophodont ( Figure 6.17 View FIGURE 6 ): there is no trace of metaloph between the mesolophule and the posteroloph. The metacone is the largest cusp, at the labial end of the posteroloph. On MUSM 2836, all transverse flexi are labially open, whereas the metaflexus is labially closed on MUSM 2837 (more worn).
Comparisons. The morphology of MUSM 2834 ( Figure 6.16 View FIGURE 6 ) is reminiscent of that found in dp4s of Eobranisamys from Santa Rosa ( Peru,?late Eocene/early Oligocene; Frailey and Campbell, 2004) and Branisamys from Salla ( Bolivia, late Oligocene; Hoffstetter and Lavocat, 1970; Lavocat, 1976), notably in lacking the connections between the second transverse cristid (metalophulid II) and the mesolophid (or with their associated cuspids). However, in Eobranisamys and Branisamys , there is a distal ectolophid between the mesolophid and the hypolophid, and a labial connection between the metalophulid I and the metalophulid II. MUSM 2834 is pentalophodont whereas the dp4s of Eobranisamys and Branisamys are hexalophodont, in showing the addition of a neolophid between the metalophulid I and the metalophulid II. MUSM 2835 ( Figure 6.15 View FIGURE 6 ) is similar in dental size to Eobranisamys , while Branisamys is significantly larger. That m2 has a pattern close to that of lower molars of Eobranisamys , which can have accessory cristids on the metalophulid I and second transverse cristid. Although the size of the fragmentary upper molars (MUSM 2836 and 2837; Figure 6.17 View FIGURE 6 ) is compatible with that of Eobranisamys , the former are tetralophodont while Eobranisamys and Branisamys have pentalophodont upper molars, with a strong metaloph. To sum up, this taxon might show close affinities to Eobranisamys , and to a lesser extent to Branisamys . However, the particular characteristics of the dp4 and the tetralophodont pattern of upper molars do not allow for a formal generic assignment. Branisamys was initially attributed to the Dasyproctidae (i.e., Cavioidae) by Lavocat (1976), but this genus may be more closely related to the Chinchilloidea following Kramarz et al. (2013) and Vucetich et al. (2015). Eobranisamys was originally assigned to the Cavioidea ( Frailey and Campbell, 2004), but its alleged close relationship with Branisamys would question, in turn, the suprafamilial attribution of Eobranisamys . In the present state, we provisionally refer the material of CTA-29 to as “ Cavioidea or Chinchilloidea indet.,” although a critical revision of Eobranisamys and Branisamys would be necessary in that purpose.
Superfamily indet.
Genus POZOMYS gen. nov.
zoobank.org/ 903578CB-4B98-4430-AF8B-5C30839265D5
Type species. Pozomys ucayaliensis , sp. nov.
Species content. Only the type species.
Etymology. From the Pozo Formation, which includes the CTA-29 locality, and mŷs, Greek for mouse.
Generic diagnosis. As for the type and only species.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.