Canaanimys sp.
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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-E522-AC20-FBFF-D64BFEAD17C2 |
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treatment provided by |
Felipe |
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scientific name |
Canaanimys sp. |
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Figure 5.1-2 View FIGURE 5 , Appendix 3
2016? Canaanimys sp. Antoine et al., Supplementary data, p. 5.
2017? Canaanimys sp. Antoine et al., Supplementary data, p. 9.
Referred material. MUSM 2645, fragmentary right
dp4 ( Figure 5.1 View FIGURE 5 ); MUSM 2646, fragmentary left lower molar ( Figure 5.2 View FIGURE 5 ).
Locality. Contamana CTA-47, Loreto Department, Peru. This is the lowermost locality having yielded rodents in the Quebrada Cachiyacu section of Contamana ( Antoine et al., 2016).
Formation and age. Pozo Formation, lower member, late middle Eocene ( Antoine et al., 2016).
Description. The brachydont dp4 (MUSM 2645; Figure 5.1 View FIGURE 5 ) is broken in its posterior part, lingually at the level of the hypolophid and labially at the level of the labial end of the posterolophid. Despite the wear, the protoconid, metaconid, and mesostylid are well-recognizable. The metalophulid I is curved and connected to the protoconid and metaconid. This cristid is thick except in its labial end, which tapers before connecting the protoconid. The posterior arm of the protoconid does not reach the metaconid. This cristid ends at mid-line of the tooth width. The mesial ectolophid is separate from the protoconid by a wide labial opening of the mesial mesoflexid. The posterior arm of the metaconid runs distally and reaches the mesostylid. Labially, at the intersection of the mesial ectolophid and distal one, there is a tiny spur, directed toward the mesostylid, probably corresponding to a very short mesolophid. There is a labial connection between the hypolophid and the posterolophid (no taeniodont). Given the short posterior arm of the protoconid and mesolophid, the anteroflexid, mesial mesoflexid, and distal mesoflexid are merged. That mixed flexid is lingually open between the mesostylid and entoconid, as well as labially between the protoconid and the mesial ectolophid.
MUSM 2646 ( Figure 5.2 View FIGURE 5 ) is a mesial fragment of a lower molar. Only the metalophulid I and a part of the second transverse crestid are visible. The latter is reduced and composed of different structures (a posterior arm of the protoconid and probably a neocristid).
Comparisons. These teeth have a size close to that of Cachiyacuy kummeli , Canaanimys maquiensis , and Eoespina / Eosachacui ( Frailey and Campbell, 2004) . In MUSM 2645 ( Figure 5.1 View FIGURE 5 ), the presence of a short posterior arm of the protoconid (not connected to the metaconid) and a strong posterior arm of the metaconid recall the conditions found in C. maquiensis . However, the discontinuity of the second transverse cristid and its reduction (although its labial part remains well-defined) is also found in Draconomys verai ( Vucetich et al., 2010) . Even though the general morphology of MUSM 2645 appears quite primitive by some characters (e.g., brachydonty and absence of taeniodonty), this tooth differs from the dp4s characterizing pre-Deseadan species for which this dental locus is known in having a mesolophid virtually undeveloped. A reduced mesolophid is also observed in dp4s of Cachiyacuy contamanensis and Canaanimys maquiensis but, in these taxa, this cristid is short and still well-recognizable. Given the scarcity and damaged condition of the available material, we tentatively and provisionally assign these teeth to? Canaanimys sp.
Gen. et sp. indet. 1
Figure 5.4 View FIGURE 5 , Appendix 3
2016? Canaanimys sp. Antoine et al., Supplementary data, p. 5.
2017? Canaanimys sp. Antoine et al., Supplementary data, p. 9.
Referred material. MUSM 2647, fragmentary right lower molar ( Figure 5.4 View FIGURE 5 ).
Locality. Contamana CTA-47, Loreto Department, Peru. This is the lowermost locality having yielded rodents in the Quebrada Cachiyacu section of Contamana ( Antoine et al., 2016).
Formation and age. Pozo Formation, lower member, late middle Eocene ( Antoine et al., 2016).
Description. MUSM 2647 ( Figure 5.4 View FIGURE 5 ) is the labial part of a right lower molar. Mesially, the tooth is broken along the posterior arm of the protoconid. Distally, only the labial extremity of the hypoconid apex is present. As the mesiolabial outgrowth of the hypoconid is not curved, the hypoflexid is straight and transverse, which clearly indicates that this specimen is a lower molar.
The size of MUSM 2647 is comparable to that of Cachiyacuy kummeli and Canaanimys maquiensis but, due to its fragmentary state, it is impossible to provide a formal taxonomic assignment of this specimen.
Gen. et sp. indet. 2
Figure 5.8 View FIGURE 5 -10, Appendix 3
2016 Cachiyacuy aff. kummeli Antoine et al. , Supplementary data, p. 5.
2016 Canaanimys cf. maquiensis Antoine et al. , Supplementary data, p. 5.
2017 Cachiyacuy aff. kummeli Antoine et al. , Supplementary data, p. 9.
2017 Canaanimys cf. maquiensis Antoine et al. , Supplementary data, p. 9.
Referred material. MUSM 2656, fragmentary right lower molar ( Figure 5.8 View FIGURE 5 ); MUSM 2657 left dP4 (Figure 5.9); MUSM 2658, fragmentary left upper tooth
( Figure 5.10 View FIGURE 5 ).
Locality. Contamana CTA-51, Loreto Department,
Peru.
Formation and age. Pozo Formation, lower member, late middle Eocene ( Antoine et al., 2016).
Description. The lower molar (MUSM 2656; Figure 5.8 View FIGURE 5 ) is heavily worn and broken posteriorly. It is tetralophodont and non-taeniodont. The second transverse cristid appears continuous but it is not rectilinear, its lingual part being distally displaced. This configuration suggests that this cristid is an association of two cristids: labially, a long, straight, and lingually oriented posterior arm of the protoconid, and labially, a short and labially oriented neomesolophid. The latter cristid originates from a faintly visible mesostylid, situated in the distal most part of a strong and long posterior arm of the metaconid.
The dP4 (MUSM 2657; Figure 5.9 View FIGURE 5 ) is damaged and eroded. This tooth is longer than wide, tetralophodont and non-taeniodont. A fractured long lingual root avoids any confusion with lower molars. The protoloph is slightly oblique (a few linguodistally directed) and parallel to the transverse and adjacent third transverse crest. Although complete, the third transverse crest is very thin in its lingual tip (where it connects the anterior arm of the hypocone) and forms a short spur forwardly oriented. This arrangement indicates that this crest is composed of a very short lingual mesolophule and a long labial mesoloph. The mure is mesiolabially directed and continuing the oblique anterior arm of the hypocone. The posteroloph is a little thickened, but neither the metaloph nor the metacone are distinct. Given the degree of wear of the tooth, it is difficult to tell if the paraflexus and mesoflexus remain open or if they are closed labially. The most posterior flexus (confluence of the metaflexus with the posteroflexus?) is labially closed, thus forming a fossette. The paraflexus and mesoflexus are roughly equal in surface whereas the most posterior flexus is more extensive, notably in width.
MUSM 2658 ( Figure 5.10 View FIGURE 5 ) shows a similar general pattern to that of the dP4 (MUSM 2657; Figure 5.9 View FIGURE 5 ), except for the mure configuration, which is longitudinal, and for the paraflexus and the most posterior flexus, which are equally sized. Moreover, on this tooth, the posteroloph displays a tiny spur that may correspond to a residual metaloph.
Comparisons. Although eroded, these teeth have a size compatible to that of the molars of Cachiyacuy kummeli , Canaanimys maquiensis , and Eoespina woodi / Eosachacui lavocati ( Frailey and Campbell, 2004) . Concerning these specimens from CTA-51, the morphology and evolutionary stage of their dental pattern is characteristic of most early caviomorphs, notably the pre-Deseadan ones. The MUSM 2657 dP4 is tetralophodont, while in Cachiyacuy contamanensis , this tooth is pentalophodont. It is worth noting that the tetralophodonty and non-taeniodonty of MUSM 2657 ( Figure 5.9 View FIGURE 5 ) are reminiscent to the conditions found on the upper molars of E. woodi / E. lavocati or even Cachiyacuy kummeli . Hence, we prefer to assign MUSM 2658 to “ Caviomorpha gen. et sp. indet. 2,” pending new findings.
Gen. et sp. indet. 3
Figure 5.14 View FIGURE 5 , Appendix 3
2016 Caviomorpha indet., sp. 1 Antoine et al., Supplementary data, p. 6.
2017 Caviomorpha indet., sp. 1 Antoine et al., Supplementary data, p. 9.
Referred material. MUSM 2660, left upper molar ( Figure 5.14 View FIGURE 5 ).
Locality. Contamana CTA-73, Loreto Department, Peru.
Formation and age. Pozo Formation, lower member, late middle Eocene ( Antoine et al., 2016).
Description. This single tooth (MUSM 2660; Figure 5.14 View FIGURE 5 ) is heavily worn and damaged. It is small, brachydont, and non-taeniodont. The protoloph is slightly oblique, well-separated, and non-parallel to the third transverse crest (mesolophule or mesoloph?). A short and faintly visible metaloph might be present, but it is entirely merged with the posteroloph. The paraflexus and the most posterior flexus (confluence of the metaflexus with the posteroflexus) are labially closed, thus forming a fossette.
Comparisons. The size of this specimen is comparable to that of Cachiyacuy kummeli , Canaanimys maquiensis , and Eoespina woodi / Eosachacui lavocati ( Frailey and Campbell, 2004) . The shape of the occlusal outline of upper molars is similar to that of E. woodi / E. lavocati , which is less transverse than that characterizing upper molars of C. kummeli and C. maquiensis . Given the lack of diagnostic characters, we provisionally assign this tooth to a Caviomorpha gen. et sp. indet. 3.
Gen. et sp. indet. 4
Figure 5.13 View FIGURE 5 , Appendix 3
2016 Caviomorpha indet. sp. 2, Antoine et al., Supplementary data, p. 6.
2017 Caviomorpha indet. sp. 2, Antoine et al., Supplementary data, p. 9.
Referred material. MUSM 2659, fragmentary right lower molar ( Figure 5.13 View FIGURE 5 ).
Locality. Contamana CTA-73, Loreto Department,
Peru.
Formation and age. Pozo Formation, lower member, late middle Eocene ( Antoine et al., 2016).
Description. The specimen MUSM 2659 ( Figure 5.13 View FIGURE 5 ) is a small fragment of the anterior part of a right lower molar. The metalophulid I, second transverse cristid, and hypolophid are recognizable. The second transverse cristid is complete but not straight, and seems to be a mixed structure including a part of the posterior arm of the protoconid labially and, lingually, a neomesolophid. Both cristids are similar in length. The branch of the posterior arm of the protoconid bears a tiny spur on its posterior edge. The ectolophid is oblique. The anteroflexid and mesoflexid appear closed lingually. This lingual closure is due to the strong development of a long posterior arm of the metaconid, which incorporates a faintly visible mesostylid, and also due to the connection between the posterior arm of the mesostylid and the anterior arm of the entoconid.
Comparisons. The morphology of this anterior fragment of lower molar is comparable to that found in most of Eocene/early Oligocene caviomorphs (all taxa from CTA-27, 29, 51 and Santa Rosa [except Eoincamys and Eopululo Frailey and Campbell, 2004 ]), notably by the configuration of the second transverse cristid (a neomesolophid + a long posterior arm of the protoconid). Its size is close to that of lower molars of C. cf. contamanensis from CTA-51, which is slightly smaller than that of C. contamanensis from CTA-27. We provisionally refer this material of CTA-73 to Caviomorpha gen. et sp. indet. 4.
Gen. et sp. indet. 5
Figure 6.13 View FIGURE 6 , Appendix 3
2016 Cachiyacuy cf. kummeli Antoine et al. , (Supplementary data, p. 9).
2017 Cachiyacuy cf. kummeli Antoine et al. , (Supplementary data, p. 9).
Referred material. MUSM 2838, right dp4 ( Figure 6.13 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 2838; Figure 6.13 View FIGURE 6 ) is worn and shows a well-marked distal contact facet. The talonid is almost twice as wide as the pinched labiolingually trigonid. It is pentalophodont with large, complete cristids and cuspids still well-defined and bulbous (except the metaconid), and it is non-taeniodont. Mesially, the protoconid is labially opposed to the metaconid, and these two cuspids are linked mesially by a curved metalophulid I, and distally by a straight and complete metalophulid II. Mediolabially, the mesial branch of the ectolophid is linguolabially oriented and not connected to the protoconid mesially. With this cristid arrangement, the hypoflexid is narrow and not mesially extensive. A strong and slightly oblique mesolophid runs mesiolingually from the ectolophid, to reach the lingual margin, where it is connected to a strong mesostylid. This latter is entirely merged with the short but elevated posterior arm of the metaconid. With the mesolophid connection and the mesial ectolophid arrangement, the mesial mesoflexid is closed lingually but open labially. The hypoconid and entoconid are labiolingually opposed. The hypoconid displays a strong and long anterior arm that connects to a short hypolophid stemming from the entoconid. The distal ectolophid is strong, almost longitudinal, and links the mesolophid and anterior arm of the hypoconid/ hypolophid junction. Lingually, neither the mesostylid nor the lingual end of the posterolophid is linked to the entoconid distally and mesially, respectively. The anteroflexid is the only flexid closed lingually (= anterofossettid).
Comparisons. MUSM 2838 ( Figure 6.13 View FIGURE 6 ) is tetralophodont like the dp4s of most pre-Deseadan caviomorphs, except Eobranisamys and Branisamys ( Hoffstetter and Lavocat, 1970; Lavocat, 1976; Frailey and Campbell, 2004), which have hexalophodont dp4s. MUSM 2838 shares with the dp4 referred to C. maquiensis (MUSM 1895) and some dp4s of C. contamanensis (MUSM 2663, 2670, and 2669), a lingual connection between the metaconid and the mesostylid, contrary to all other pre-Deseadan caviomorph species documented by dp4s. Yet, on MUSM 2838, the second transverse cristid does not form a longitudinal cristid, connected to the mesolophid, contrary to what is observed in dp4s of C. maquiensis . On MUSM 2838, the protoconid is clearly separate from the mesial ectolophid, as in Eosallamys simpsoni and some dp4s of Eoespina / Eosachacui (as well as in Eobranisamys and Branisamys ; Hoffstetter and Lavocat, 1970; Lavocat, 1976; Frailey and Campbell, 2004). This character is not found in Cachiyacuy and Eosallamys paulacoutoi . Thus, this specimen from CTA-61 is provisionally identified as Caviomorpha gen. et sp. indet. 5.
Gen. et sp. indet. 6
Figure 6.14 View FIGURE 6 , Appendix 3
2016 Caviomorpha indet., sp. 2 Antoine et al., Supplementary data, p. 9.
2017 Caviomorpha indet., sp. 2 Antoine et al., Supplementary data, p. 9.
Referred material. MUSM 2839, right M1 or 2 ( Figure 6.14 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 upper molar (MUSM 2839; Figure 6.14 View FIGURE 6 ) is particularly worn and eroded, and also distolabially broken. Its crown outline is quadrate in occlusal view. There are four crests but the posteroloph exhibits a short enamel spur on its mesial edge (remnant metaloph?). The anteroloph and protoloph are linked labially and broadly merged lingually due to wear. This tooth is non-taeniodont, and the mure is longitudinal and well-differentiated with respect to the oblique anterior arm of the hypocone and the transverse protoloph. Centrally, there is a strong but moderately long mesolophule, transverse and parallel to the protoloph. Labially, the mesolophule is connected to a strong mesostyle. Although the upper molar is broken distolabially (at the place where a metacone would have occurred), a small enamel ridge indicates that the mesostyle was connected to the metacone-posteroloph complex. In contrast, mesially, the mesostyle remains well-separate from the paracone (mesoflexus labially open). The parafossette is small, narrow, and labially limited, while the most posterior fossette (confluence between the metaflexus and posteroflexus) is broader and more lingually extended.
Comparisons. This upper molar is the smallest specimen discovered from CTA-29. The small size of this tooth, its quadrate shape and its tetralophodonty (with a possible relic of a metaloph), recall the dental pattern of Eoespina / Eosachacui . However, as for MUSM 2660 from CTA-73, due to wear, it is impossible to propose a formal taxonomic assignment.
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