Taowu Liui

''Taowu'' is an extinct genus of machairodonts, a type of saber-toothed cat. It lived during the Early Pleistocene about 2.5 million years ago in East Asia. So far, only one skull is known, found in northern China. Based on this, a relatively small representative of the saber-toothed cats can be reconstructed, which only reached the size of a present-day leopard. In its dentition characteristics, it mediates between phylogenetic older forms such as ''Amphimachairodus'' and younger members such as ''Homotherium''. The genus was scientifically described in 2022, but the find material was recovered as early as the 1930s.

Description

''Taowu'' was a rather small representative of the saber-toothed cats. It reached about the size of a present-day leopards. Found so far is a nearly complete skull of 23.5 cm length and 13.4 cm width, measured across the zygomatic arches. Only the articular surface on the occipital bone is missing from this one. In top view, the skull was relatively slender, comparatively narrower than in ''Homotherium'' or ''Xenosmilus'', and possessed a rounded snout region. The snout did not taper behind the canine, but continuously increased in width posteriorly. Likewise, a cranial narrowing behind the orbits was only rather weakly pronounced. In lateral view, the frontal line showed a gentle uparching, and the nasal opening was recessed and concavely indented relative to the premaxilla. The incisor row thus appeared much more prominent than in, for example, ''Amphimachairodus''. In plan view, the frontal area was broad. The nasal bones widened posteriorly. The infraorbital foramen was at the level of the fourth premolar, as was the anterior edge of the orbit. Bony ridges attached to the frontal bone, which united to form a parietal crest. The zygomatic arch bulged strongly dorsally. On the underside of the skull, the tympanic bulla was markedly distended. As a diagnostic feature, the glenoid fossa was on a raised platform, more prominent than in ''Amphimachairodus'', and was very wide. The anterior palatal window was at the level of the canine, and the largest posterior one was at the level of the third premolar. The upper dentition consisted of three incisors, one canine, two premolars, and two molars per half of the jaw. The incisors formed a closed arch and increased in size from the inside to the outside. An additional cusp existed on the third incisor. The canine tooth protruded up to 7.4 cm from the jaw and was flat blade-shaped in cross-section. Both the anterior and posterior edges showed fine serration. Adjacent to the canine, a diastema separated the anterior from posterior dentition. Unlike some other saber-toothed cats such as '' Lokotunjailurus'', the second premolar was absent. The third and thus most anterior premolar was not reduced in size, which differs from ''Homotherium'', '' Lokotunjailurus'', or ''Xenosmilus''. Overall, the tooth appeared elongated at a length of just under 2 cm, as did the much larger posterior premolar, which grew to a good 3.4 cm in length. The typical pointed cusps, the para-, meta-, and protoconus, existed on this, the latter only being small in formation. The anterior shear edge, the parastyle, had an elongate shape, from which the anteriormost section, the preparastyle, stood out only imperceptibly.

Fossil finds

The only fossil find of ''Taowu'' to date comes from Fancun, a locality about 36 km east of the township of Taigu, which in turn is part of the city of Jinzhong in the Chinese Shanxi province. The site and other areas in the region were excavated as early as the 1930s by American paleontologist Childs Frick. The various localities yielded numerous fossil materials, including several carnivores such as ''Homotherium'' as another representative of the saber-toothed cats, an extinct form of the lynx as well as the badger, ''Xenocyon'' as a member of the dogs, and the hyena ''Pachycrocuta''. In addition, early relatives of modern horses also appeared. Especially the latter mentioned imply a predominant position in the Pleistocene, with the lower section being more likely.Lorenzo Rook: ''The Plio-Pleistocene Old World Canis (Xenocyon) ex gr. falconeri.'' Bollettino della Societa Paleontologica Italiana 33 (1), 1994, S. 71–82Véra Eisenmann und Tao Deng: ''Equus qingyangensis (Equidae, Perissodactyla) of the Upper Pliocene of Bajiazui, China: Evidence for the North American origin of an Old World lineage distinct from E. stenonis.'' Quaternaire 2 (2), 2005, S. 113–122

Classifications

''Taowu'' is a genus from the extinct subfamily of saber-toothed cats (Machairodontinae) within the family of cats (Felidae). The saber-toothed cats represent an ancient branch of cats, which according to molecular genetics studies, forms the sister group of today's big cats and small cats. Their separation from the common branch occurred about 20 million years ago in the Lower Miocene.Johanna L. A. Paijmans, Ross Barnett, M. Thomas P. Gilbert, M. Lisandra Zepeta-Mendoza, Jelle W. F. Reumer, John de Voss, Grant Zazula, Doris Nagel, Gennady F. Baryshnikov, Jennifer A. Leonard, Nadine Rohland, Michael V. Westbury, Axel Barlow, Michael Hofreiter: ''Evolutionary history of sabre-toothed cats based on ancient mitogenomics.'' Current Biology 27, 2017, S. 3330–3336, doi:10.1016/j.cub.2017.09.033Michael V. Westbury, Ross Barnett, Marcela Sandoval-Velasco, Graham Gower, Filipe Garrett Vieira, Marc de Manuel, Anders J. Hansen, Nobuyuki Yamaguchi, Lars Werdelin, Tomas Marques-Bonet, M. Thomas P Gilbert, Eline D Lorenzen: ''A genomic exploration of the early evolution of extant cats and their sabre-toothed relatives.'' Open Research Europe 1, 2021, S. 25, doi:10.12688/openreseurope.13104.2Alexandre Hassanin, Géraldine Veron, Anne Ropiquet, Bettine Jansen van Vuuren, Alexis Lécu, Steven M. Goodman, Jibran Haider, Trung Thanh Nguyen: ''Evolutionary history of Carnivora (Mammalia, Laurasiatheria) inferred from mitochondrial genomes.'' PLOS One 16 (3), 2021, S. e0249387, doi:10.1371/journal.pone.0240770 The feature that gave saber-toothed cats their name is their significantly enlarged canine teeth. However, this shows certain variations within the kinship community, which led to the establishment of different subgroups. Here, the Machairodontini have saber-like canines, the Smilodontini have dagger-like canines, and the Metailurini have less conspicuously large canines.Paolo Piras, Daniele Silvestro, Francesco Carotenuto, Silvia Castiglione, Anastassios Kotsakis, Leonardo Maiorino, Marina Melchionna, Alessandro Mondanaro, Gabriele Sansalone, Carmela Serio, Veronica Anna Vero, Pasquale Raia: ''Evolution of the sabertooth mandible: A deadly ecomorphological specialization.'' Palaeogeography, Palaeoclimatology, Palaeoecology 496, 2018, S. 166–174, doi:10.1016/j.palaeo.2018.01.034 With its leopard-like body size, ''Taowu'' represents one of the smallest representatives of the saber-toothed cats of the Pliocene. In overall dentition, the form can be assumed to be somewhat intermediate between the more primitive ''Amphimachairodus'' and the terminal form ''Homotherium'' within the Machairodontini. This is recognizable, for example, from the third premolars, which are only slightly reduced in size. On the other hand, the anteriorly shifted incisors also suggest certain more modern characteristics.Paolo Piras, Daniele Silvestro, Francesco Carotenuto, Silvia Castiglione, Anastassios Kotsakis, Leonardo Maiorino, Marina Melchionna, Alessandro Mondanaro, Gabriele Sansalone, Carmela Serio, Veronica Anna Vero, Pasquale Raia: ''Evolution of the sabertooth mandible: A deadly ecomorphological specialization.'' Palaeogeography, Palaeoclimatology, Palaeoecology 496, 2018, S. 166–174, doi:10.1016/j.palaeo.2018.01.034

The skull underlying the genus ''Taowu'' was found as early as the 1930s in Fancun, part of the city of Jinzhong, in the Chinese Shanxi province. It was mentioned in individual publications in which various researchers classified it as belonging to ''Machairodus'', but a precise characteristic description was not developed.Germaine Petter und F. Clark Howell: ''Machairodus africanus Arambourg, 1970 (Carnivora Mammalia) du Villafranchien d'Aïn Brimba, Tunisie.'' Bulletin du Muséum National d'Histoire Naturelle 4 (9), 1987, S. 97–119

Denis Geraads, Tanju Kaya und Vahdet Tuna: ''A skull of Machairodus giganteus (Felidae, Mammalia) from the Late Miocene of Turkey.'' Neues Jahrbuch für Geologie und Paläontologie Monatshefte 2004 (2), 2004, S. 95–110 Studies in 2022 necessitated a reevaluation. Jiangzuo Qigao and colleagues then established ''Taowu'' as a distinct form of saber-toothed cat in their scientific first description and presented the skull in detail. The generic name ''Taowu'' refers to the creature of the same name in Chinese mythology. Its striking characteristics include powerful tusks reminiscent of saber teeth. The species ''T. liui'', introduced together with the genus, uses its epithet to honor the Chinese scientist Liu Jinyi, who had made significant contributions to the study of Pleistocene East Asian predators.

Below is a phylogenetic tree of the Machairodontinae, based on the work of Jiangzuo and colleagues (2022).

References

{{Machairodontinae
Machairodontinae
Fossil taxa described in 2022
Pleistocene mammals of Asia
Fossils of China
Pleistocene carnivorans