Ninumbeehan
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| Ninumbeehan | |
|---|---|
 | |
| Life restoration | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Tetrapoda |
| Order: | †Temnospondyli |
| Suborder: | †Stereospondyli |
| Family: | †incertae sedis |
| Genus: | †Ninumbeehan So et al., 2024[1] |
| Species: | †N. dookoodukah |
| Binomial name | |
| †Ninumbeehan dookoodukah So et al., 2024[1] | |
Ninumbeehan (from the Shoshone words ninumbee for mountain-dwelling Little People, -han as a possessive affix) is a genus of stereospondyl temnospondyl from the Late Triassic Jelm Formation of Wyoming. It is represented by the type species, Ninumbeehan dookoodukah, which was named from a holotype and three paratypes; the holotype is from the Serendipity site within the informal Serendipity beds.
Ninumbeehan dookoodukah is one of several small-bodied Late Triassic temnospondyls that have been named from North America, including the uncertain Latiscopus disjunctus,[2] Rileymillerus cosgriffi,[3] and Chinlestegophis jenkinsi.[4] It also shares some similarities with the small-bodied Almasaurus habbazi[5] from the Late Triassic of Morocco. There are two autapomorphies of N. dookoodukah: (1) a ventrally sloping unornamented posterior process along the midline formed by the postparietals; and (2) anterior dorsal ribs subequal in length to the dorsoventral height of the skull and mandible.[1] It shares with C. jenkinsi and perhaps R. cosgriffi the absence of a distinct lacrimal, but lacks a lateral exposure of the palatine that is found in both of these taxa. A falciform crest of the squamosal, posteriorly situated pineal foramen, otic notch, and developed tabular horn further separate it from R. cosgriffi. The otic notch is more developed than in C. jenkinsi, the cultriform process is narrower, and the supratemporal is subrectangular, more like other stereospondyls than like the subcircular element in C. jenkinsi. The absence of a lacrimal separates it from A. habbazi, as does the expanded posterolateral region of the premaxilla along the lateral narial margin, a wider posterior region of the parietal, a flat cultriform process, and a palatoquadrate fissure.
Much of the skeleton is known for N. dookoodukah. The holotype is represented by a skull, lower jaws, and pectoral girdle in articulation, along with loosely articulated/associated left forelimb, ribs, and intercentra. Other postcrania may be present. The described paratypes also comprise skulls of varying completeness in articulation or association with the lower jaws, pectoral girdle, and axial column. The largest skull is approximately 7 cm in length, larger than C. jenkinsi and R. cosgriffi. Lateral line grooves indicate an aquatic life history, while the wedge-shaped lateral profile is thought to be evidence for inferred burrowing behavior. Like C. jenkinsi and modern caecilians, there is a second row of teeth on the coronoids that lie medial to the primary marginal row on the dentary, a feature originally proposed to link C. jenkinsi to this modern group[4] but subsequently disputed as such a feature occurs in some other stereospondyls.[6][7] The function of the greatly elongated anterior ribs of N. dookoodukah remains unclear. The limbs are relatively small compared to the skull (about one-third of the length), further suggesting that burrowing was accomplished primarily through head-based functionality.