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Sikuomys mikros
Taxonomy
Sikuomys mikros was named by Eberle et al. (2023). Its type specimen is UAMES 51511, a tooth (RM2), and it is a 3D body fossil. Its type locality is Paul’s Pearls, Colville River, which is in a Maastrichtian coarse channel fill sandstone in the Prince Creek Formation of Alaska. It is the type species of Sikuomys.
Synonymy list
| Year | Name and author |
|---|---|
| 2023 | Sikuomys mikros Eberle et al. |
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If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
†Sikuomys mikros Eberle et al. 2023
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| J. J. Eberle et al. 2023 | Tiny eutherian mammal whose molars are approximately two-thirds to three-quarters the size of Gypsonictops hypoconus; P4, P5, and upper molars with procumbent protocone; P4 with metacone, but lacking conules and pre- and postcingula; P5 molariform and bearing weak pre- and postcingula; upper molars with large parastyle anterolabial to the paracone, small conules, pre- and postcingula that do not extend labially past the paraconule and metaconule, respectively, but postcingulum extends lingually beyond margin of protocone; M1 with straight labial margin, and M2 with shallow ectoflexus; p5 bicuspid with tall protoconid and lower metaconid, and a broad anterior cingulid with no paraconid. Lower molars with metaconid slightly taller than, or subequal in height to, protoconid, small anteriorly projecting paraconid lingual to the midline but anterolabial to the metaconid, and cristid obliqua contacts the posterior wall of the trigonid below the protocristid notch; hypoconulid closer to entoconid on m3. Differs from Gypsonictops spp. in smaller size, absence of a postcingulum on P4, weak pre- and postcingula on P5, upper molars with smaller conules, narrower pre- and postcingula that do not extend labially past conular region, but postcingulum extends lingually past margin of protocone, M2 with shallower ectoflexus and smaller parastylar and metastylar lobes, and lower molars with a less anteroposteriorly compressed trigonid. P4 differs from P4s of G. lewisi and G. clemensi in presence of a metacone. P4, P5 and upper molars differ from those of G. clemensi and G. lewisi in having a procumbent protocone. Upper molars differ from Leptictis in lacking a large hypocone. The p5 differs from p5 of Leptictis and many p5s of Gypsonictops in lacking a paraconid. Lower molars differ from those of G. hypoconus, G. lewisi and G. clemensi in that the metaconid is slightly taller than the protoconid or the two cusps are subequal in height. Lower molars differ from those of Leptictis in having a lingual paraconid and lacking an entoconulid. |
Measurements
No measurements are available
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| Source: f = family, subc = subclass, subp = subphylum, p = phylum | |||||
| References: Kielan-Jaworowska et al. 2004, Kiessling 2004, Ji et al. 2002, Lillegraven 1979, Carroll 1988 | |||||
Age range: Early/Lower Maastrichtian or 72.20000 to 66.00000 Ma
Collections (3 total)
| Time interval | Ma | Country or state | Original ID and collection number |
|---|---|---|---|
| Early/Lower Maastrichtian | USA (Alaska) | Gypsonictops sp. (14495) Sikuomys mikros (type locality: 231243 231244) |