Tonomochota
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| Tonomochota Temporal range: Late Pleistocene | |
|---|---|
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Lagomorpha |
| Family: | Ochotonidae |
| Genus: | †Tonomochota Tiunov & Gusec, 2021 |
| Type species | |
| †Tonomochota khasanensis Tiunov & Gusec, 2021 | |
| Other species | |
| |
Tonomochota is an extinct genus of ochotonid endemic to the Russian Far East region that is known currently from the Late Pleistocene and possibly the Early Holocene. Dental remains belonging to the genus were uncovered from fossil deposits in multiple eastern Russian caves and later formally described by Russian researchers starting in 2021. The genus name is an anagram of the extinct ochotonid genus Ochotonoma. There are four species assigned to Tonomochota in total.
Tonomochota is one of two ochotonid genera known from the Pleistocene, the other being the extant Ochotona, which contains pikas. It would have coexisted with a few extinct small mammals along with plenty of extant small mammal species in a blend of forested and open habitats.
Classification
From 2012 to 2016, paleontologists excavated dental fossils belonging to the Ochotonidae from two eastern Russian limestone caves: Sukhaya Cave and Tetyukhinskaya Cave. The fossils found in both caves date to the Late Pleistocene and may have accumulated because of predatory animal and bird activities. Excavators recovered 17 teeth of undescribed ochotonid species from Tetyukhinskaya Cave from 2012 to 2015; they later uncovered 27 additional ochotonid teeth from Sukhaya Cave in 2016.[1]
In 2021, the Russian paleontologists Mikhail P. Tiunov and Alexander E. Gusev erected the genus Tonomochota, describing its naming origin as an anagram of the fossil ochotonid genus Ochotonoma. The type and first newly recognized species is Tonomochota khasanensis, thus making the genus type locality Sukhaya Cave; the species name derives from the Khasansky District where the cave is found. The second species that the two researchers erected was T. sikhotana from Tetyukhinskaya Cave, whose name derives from the Sikhote-Alin mountain range in Primorsky Krai where the cave is located. The third species they named was T. major from Sukhaya Cave, its name being in reference to its large size.[1]
Another series of ochotonid dental fossil excavations were done at Korydornaya Cave at the Jewish Autonomous Oblast at Russia from 2017 to 2018. In 2023, Russian paleontologists Alexander E. Gusev and Mikhail P. Tiunov studied the ochotonid teeth and erected T. khinganica, named after the Greater Khingan mountain range in China.[2]
Tonomochota belongs to the Ochotonidae, of which the only extant genus is Ochotona (which contains pikas). The family is divided into two subfamilies, the Ochotoninae and Sinolagomyinae.[1] The earliest fossil record of the Ochotonidae is recorded in the early Late Oligocene of Mongolia. The Sinolagomyinae was the earlier-appearing family known initially from Mongolia and China that later dispersed to Europe, Africa, and North America and lasted up to the Middle Miocene. The Ochotoninae made its first appearance in the Eurasian landmass during the Early Miocene and was especially diverse during the Middle Miocene. During the Late Miocene, newer ochotonine genera appeared in response to drier and cooler climates that led to more open environments. The evolutionary diversity of the Ochotoninae declined beginning in the Pliocene likely due to competition with the cricetid subfamily Arvicolinae, leading to the eventual extinction of most ochotonid genera by the late Pliocene.[3] Ochotona and Tonomochota are the only two ochotonid genera known from the Pleistocene.[1]