Yoshi (Genus)

''Yoshi'' is an extinct genus of machairodontine sabertooth cat in the tribe Metailurini. Its remains were first discovered in Pikermi, Greece, and were assigned by Reinhold Friedrich Hensel to ''Machairodus'' (under the new species ''M. parvulus''. In 1938, Miklós Kretzoi assigned it to a new genus, ''Pikermia''. Subsequently, it was realised that the Greek taxon was closely related to another from China, then called ''Parapseudailurus minor'', and both were synonymised. In 2014, a new genus, ''Yoshi'', was erected to encompass the two, resurrecting ''Y. minor'' as a valid species. As ''M. parvulus'' was a ''nomen dubium'', a new species, ''Yoshi garevskii'', was designated as the type. In the intervening years, three more species have been assigned to the genus: ''Y. faie'', ''Y. obscura'', and ''Y. yongdengenesis''.

In some regards, such as the shape of its skull, ''Yoshi'' was convergent with cheetahs, and it was originally suggested that it may have been more cursorial (adapted for fast running) than other metailurines. However, the anatomy of its postcranial skeleton, such as the fact that its hind limbs were longer than its forelimbs, suggest that, while probably somewhat cursorial, it was not to the same extent as cheetahs. ''Yoshi'' instead had several adaptations for leaping, like many modern cats. It appears to have frequented open habitats more often than contemporary machairodonts.

Taxonomy

Early history

In 1862, Reinhold Friedrich Hensel described the species ''Machairodus parvulus'' based poorly preserved skulls from Pikermi, Greece, which he believed came from an animal the size of a lynx. In 1938, Miklós Kretzoi reassigned ''M. parvulus'' to a new genus, ''Pikermia'', creating the new combination ''Pikermia parvula''. In the same paper, he suggested that "'' Metailurus''" ''minor'', from China, could be reassigned to a genus of its own, ''Parapseudailurus''. However, in 1951, Erich Thenius suggested that ''P. minor'' represented the same taxon as Hensel's ''M. parvulus'', a conclusion also reached by G. D. Beaumont in 1961, who went as far as assigning a mandible from Iran to the latter. Consequently, ''P. minor'' was treated as a synonym of ''M. parvulus'' by subsequent authors. Further material from southern/southeastern Europe and Iran was assigned to ''M. parvulus'' over the years, though much of it is incomplete.

Reclassification as a new genus

In 2015, Nikolai Spassov and Denis Geraads published a paper discussing the taxonomy of the aforementioned taxa. They concluded that Hensel's ''Machairodus parvulus'' was a nomen dubium, due to the generally fragmented nature of all material assigned to the species. All of the remains were assigned to a new genus, ''Yoshi'', named after Spassov's pet cat. Two species were assigned: the type species, ''Y. garevskii'', and ''Y. minor'', the taxon discussed by Kretzoi. In 2022, two new species ''Yoshi faie'' and ''Yoshi yongdengensis'' were proposed based on fossils found in northeastern China. The next year, a paper discussing the predatory mammals of the Langebaanweg locality in South Africa assigned a fifth species, ''Y. obscura'', to the genus. ''Y. obscura'' had previously been assigned to '' Adelphailurus'', ''Felis'', ''Megantereon'', and '' Metailurus''. The authors noted that the very small taxon '' Tchadailurus adei'' seemed very close to the genus ''Yoshi'', though a synonymy was not proposed in the text.

Below is a cladogram depicting the phylogenetic analysis from that paper:

Description

''Yoshi'' was a fairly large metailurine. In the paper describing it, ''Y. garevskii'' was described as being intermediate in size between a lynx and a cheetah, though it was closer to the latter, with an estimated body mass of . The largest, ''Y. yongdengensis'', fell within a similar size range. Though too fragmentary for precise estimates, ''Y. obscura'' is believed to have been the smallest, roughly the size of a female leopard.

Skull and dentition

The skull length of the ''Y. garevskii'' type specimen, KAR-69, was in length. The skull of ''Y. garevskii'' is short, broad and high, and is morphologically quite similar to that of cheetahs, with a facial region that was similarly long and sloping. However, that of ''Y. minor'' was longer, and appears to have been less sloping. The frontal area in ''Y. garevskii'' bulged outwards, similar to cheetahs and snow leopards, while that of ''Y. minor'' was somewhat flatter. The two species' skulls also differed in that the muzzle of ''Y. garevskii'' was steeper, and the orbits (eye sockets) were elevated on the skull. On the frontal bone, the zygomatic processes are short and rounded, like those of cheetahs. The zygomatic arches are broad and thick, though differ from modern large felids in that their bases are narrower.

''Yoshi'''s dentition was dissimilar to that of other machairodonts. The upper canines were short and uncrenulated. The lower canines, too, were small, and hardly surpassed the level of the upper incisors' alveoli while the jaw was closed. The diastema (gap) between the canines and the cheek teeth (premolars and molars) was fairly small. The third upper and lower premolars lacked a mesial accessory cuspid. The first upper molar was small and button-shaped, while the equivalent lower molar bore a distinct talonid.

Postcranial skeleton

The postcranial skeleton of ''Yoshi'' is best known from a specimen from Greece, initially assigned to "''Metailurus parvulus''" (''Y. garevskii''). The specimen consists of a mandible, most limb elements, some cervical (neck) and thoracic (upper back) vertebrae, and ribs. The fossa for the teres major covers half of the scapula's posterior (rearward) border, and is well defined by a prominent crest. The head of the humerus is almost circular in outline. The lateral compression of the humeral shaft is comparable to that of leopards, being thicker than that of lions and cheetahs. The crest at the posteromedial (rear middle) margin of the ulna was well-developed, providing a strong insertion point for the large head of the triceps brachii. Unlike other machairodontines (with the exception of ''Homotherium''), the trochlear notch lacked a groove on its superomedial (above and at the midline) edge.

Palaeobiology

Initially, based on similarities between ''Yoshi'' and modern cheetahs, it was suggested that the former may have been cursorial to a similar degree to the latter. However, analysis of the postcranial skeleton indicates that this cursoriality was only moderate: the ovoid shaft cross-section of the femoral shaft, greater in diameter transversely (across) than anteroposteriorly (from front to back), which is a trait associated with reduced cursoriality. Furthermore, the shaft bows anteriorly (forwards), and the hind limbs were somewhat longer than the forelimbs, typical of felids with leaping abilities. Overall, ''Yoshi'' appears to have been intermediate between cursorial and non-cursorial machairodonts, and was more well-adapted to open environments than larger contemporaries, such as ''Paramachaerodus''.

Distribution and palaeoenvironment

Specimens assigned to ''Yoshi'' have been recovered from Greece, Spain, Ukraine, China, and Iran, though with the exception of the Greek and Chinese fossils, most are too fragmentary to confidently assign to the genus. The most complete postcranial skeleton of ''Yoshi'' is known from the K1 locality of northern Greece, which also preserves fossils from the suid ''Microstonyx'', the giraffids ''Helladotherium'', ''Palaeotragus'', and ''Samotherium'', the antelopes ''Gazella'' and ''Tragoportax'', the equid ''Hipparion'', the chalicothere ''Ancylotherium'', the aardvark ''Orycteropus'', and possible remains from the hyena ''Adcrocuta'' and the elephant ''Choerolophodon''. The Chinese ''Yoshi'' species come from the end-Miocene Xingjiawan locality, a humid environment consisting open and forested biomes. The Xingjiawan preserves the elephant ''Stegodon'', the hyaenids ''Adcrocuta'', ''Hyaenictitherium'' and ''Ictitherium'', and the felids ''Amphimachairodus'' and ''Pristifelis''.

References

{{Taxonbar, from1=Q28432831, from2=Q120433497, from3=Q107410997, from4=Q107411031, from5=Q120433536, from6=Q122047315

Metailurini
Miocene carnivorans
Miocene genus extinctions
Prehistoric carnivoran genera
Miocene mammals of Europe
Fossil taxa described in 2014