Baiotomeus russelli, S.Scott & C.Fox & P.Youzwyshyn, 2002
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publication ID |
https://doi.org/ 10.5281/zenodo.13285980 |
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persistent identifier |
https://treatment.plazi.org/id/039F87B0-0D63-FF86-AA5B-FAEFFD42FBB8 |
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treatment provided by |
Felipe |
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scientific name |
Baiotomeus russelli |
| status |
sp. nov. |
Baiotomeus russelli sp. nov.
Fig. 1D View Fig ; Table 2.
Holotype: UALVP 18787 , isolated left P4, Fig. 1D View Fig .
Type locality and horizon: Cochrane 2, Paskapoo Formation, southwestern Alberta.
Age and distribution: Earliest Tiffanian of Alberta (type locality) .
Etymology: Named after L.S. Russell for his pioneering research on the mammals from Cochrane 2.
Material.—UALVP 18788, 42866–42871, 45150, 45151, P4s (total: 9).
Diagnosis.—Smaller than other species of Baiotomeus ; anteroposterior length of P4 approximately 45 percent less than P4, Baiotomeusdouglassi ( Simpson, 1935a), and approximately 40 percent less than P4, Baiotomeuslamberti Krause, 1987; differs further from all other species of Baiotomeus in
P4 having pronounced curvature of the cusp rows, and a relatively better developed, more cuspate anterolabial lobe.
Description.—P4: Cusp formula, (3–4)5:7–8:0. P4 is kidney−shaped in occlusal view: its anterior and posterior ends are narrow but rounded, and the anterolabial lobe is poorly to moderately developed.The cusps on the anterolabial lobe may be only tiny cuspules or may be nearly as large as those in the external row.The cusps of the external row curve lin − gually; the third cusp is the largest in the row and the largest on the crown.The middle row of cusps increases in height posteriorly to the fifth cusp and decreases thereafter; the external cusp row is about two−thirds the length of the middle row.The first and second cusps are smallest in the row.The enamel is weakly wrinkled on all specimens.
Remarks.—In occlusal and lateral aspects, P4 of B. russelli strongly resembles that in B.douglassi and B.lamberti , but is much smaller.Further, P4 of B. russelli is distinct in the greater curvature of the cusp rows and in the greater change in cusp height along the middle row.
At present, P4s are the only specimens from Cochrane 2 that we can identify as pertaining to B. russelli .Although knowledge of this species is limited, we consider its naming to be justified based on the diagnostic morphology of ultimate fourth premolars in ptilodontids generally ( Krause 1982, 1987) and the unique structure of these teeth.
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