Biology:Machairodus

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Short description: Extinct genus of carnivores

Machairodus
Temporal range: Middle Miocene to Pleistocene[1]
Machairodus aphanistus - Cerro de los Batallones - Museo Arqueológico Regional CAM.JPG
M. aphanistus skull
Scientific classification e
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Suborder: Feliformia
Family: Felidae
Subfamily: †Machairodontinae
Tribe: †Machairodontini
Genus: †Machairodus
Kaup, 1833
Type species
†Machairodus aphanistus
Kaup, 1832
Species
  • M. alberdiae Ginsburg et al., 1981
  • M. aphanistus Kaup, 1832
  • M. laskerevi Sotnikova, 1992[2]
  • M. robinsoni Kurtén, 1975
  • M. horribilis Schlosser, 1903
  • M. lahayishupup Orcut, 2021

Machairodus (from Greek: μαχαίρα machaíra, 'knife' and Greek: ὀδούς odoús 'tooth')[3] is a genus of large machairodont or ''saber-toothed cat'' that lived in Africa, Eurasia and North America during the late Miocene. It is the animal from which the subfamily Machairodontinae gets its name and has since become a wastebasket taxon over the years as many genera of sabertooth cat have been and are still occasionally lumped into it.

History of research

Early restoration by Lancelot Speed from 1905 depicting Machairodus with tiger-like markings.

Machairodus was first named in 1832, by German Naturalist Johann Jakob Kaup. Though its remains had been known since 1824, it was believed by Georges Cuvier that the fossils had come from a species of bear, which he called Ursus cultridens (known today as Megantereon) based on composite sample of teeth from different countries, species and geologic ages, leading to what would become a long series of complications. Kaup however, recognized the teeth as those of felids and promptly reclassified the existing specimens as Machairodus, including M. cultridens in it. The name quickly gained acceptance and by the end of the 19th century, many species of felid or related feliform (such as nimravids) were lumped into the genus Machairodus, including but not limited to Sansanosmilus, Megantereon, Paramachairodus, Amphimachairodus, Nimravides, and Homotherium among others. This would eventually turn Machairodus into something of a wastebasket taxon, which would be rectified with the discoveries of more complete skeletons of other machairodonts.[4]

  • Machairodus irtyschensis and Machairodus ischimicus were described in 1936.[5]
  • Machairodus robinsoni was described in 1976.[6] It was at one point referred to the genus Miomachairodus.[7]
  • Machairodus laskarevi was described in 1978.[8]
  • Machairodus alberdiae was first described in 1981,[9] and extensively compared and retained as valid in 2019.[10]
  • Machairodus kurteni was described in 1991.[11] It was later referred to the genus Amphimachairodus.

Description

In general Machairodus was similar in size to a modern lion or tiger, at 2 m (6.6 feet) long and standing about 1 m (3.3 feet) at the shoulder.

M. aphanistus from the Mediterranean late Miocene is known to be rather tiger-like in size and skeletal proportions, with a mass of 100 kg (220 pounds) to 240 kg (530 pounds). It was similar to the related Nimravides of North America. The skeleton also indicates that this species would have possessed good jumping abilities.[12]

M. alberdiae was contemporary with M. aphanistus in Cerro de los Batallones fossil deposits and was smaller and more primitive in anatomical features and would not have exceeded 100 kg (220 pounds).[13]

M. horribilis of China is the one of largest known species of the genus, weighing around 405 kg (893 pounds). This is comparable in size to the much later Smilodon populator.[14] Its skull, measuring upwards of 16 inches (41 cm) in length, is one of the largest known skulls for any machairodont, with only a recently described S. populator skull rivaling it in size, with the latter cat outweighing M. horribilis at 960 lb (440 kg).[15][16]

The species M. lahayishupup of North America was also quite large; fossil humerus bones measuring 18 in (46 cm) attributed to the species suggest that this cat was far larger than a modern lion, which has a 13 in (33 cm) humerus. It is estimated to have weighed between 241 and 348 kg, with a mean weight of 277 kg; one particularly large specimen was estimated to weigh 410 kg. Until its discovery, no true species representative of the genus Machairodus had been described from North America, as they had been reassigned to other genera, such as Nimravides and Amphimachairodus. Its presence in North America suggests that either there was a widespread population of this genus of cat throughout Africa, Eurasia and North America or simultaneous instances of independent evolution in machairodonts on multiple continents during the Miocene.[17][18][19]

Overall, the skull of Machairodus was noticeably narrow compared with the skulls of extant pantherine cats, and the orbits were relatively small. The canines were long, thin and flattened from side to side but broad from front to back like the blade of a knife, as in Homotherium. The front and back edges of the canines were serrated when they first grew, but these serrations were worn down in the first few years of the animal's life. However, a skull of M. horribilis was shown to be similar to extant pantherines in some cranial characters, suggesting new evidence for the diversity of killing bites even in the largest saber-toothed carnivorans, offering an additional mechanism for the mosaic evolution leading to functional and morphological diversity in sabertooth cats.[20]

Machairodus probably hunted as an ambush predator. Its legs were too short to sustain a long chase, so it most likely was a good jumper, and used its canines to cut open the throat of its prey. Its teeth were rooted to its mouth and were as delicate as those in some related genera, unlike most saber-toothed cats and nimravids of the time, which often had extremely long canines which hung out of their mouths. The fangs of Machairodus, however, were able to more easily fit in its mouth comfortably while being long and effective for hunting.[21] Despite its great size, the largest example of Machairodus, M. horribilis was better equipped to hunt relatively smaller prey than Smilodon, as evidenced by its moderate jaw gape of 70 degrees, similar to the gape of a modern lion.[15]

Classification

M. aphanistus skeleton from Cerro de los Batallones

The fossil species assigned to the genus Machairodus were divided by Turner into two grades of evolutionary development, with M. aphanistus and the North American "Nimravides" catacopis representing the more primitive grade and M. coloradensis and M. giganteus representing the more derived grade.[22] The characteristics of the more advanced grade include a relative elongation of the forearm and a shortening of the lumbar region of the spine to resemble that in living pantherine cats.[22] Subsequently, the more derived forms were assigned a new genus, Amphimachairodus, which includes M. coloradensis, M. kurteni, M. kabir and M. giganteus.[2] In addition, M. catacopsis was reclassified as N. catacopsis.[23]

Paleobiology

Restoration

Studies of Machairodus indicate that the cat relied predominantly on its neck muscles to make the killing bite applied to its victims. The cervical vertebrae show clear adaptations to making vertical motions in the neck and skull. There are also clear adaptations for precise movements, strength, and flexibility in the neck that show compatibility with the canine-shearing bite technique that machairodontine cats are believed to have performed. These adaptations are believed to have also been partial compensation in this primitive machairodont against the high percentage of canine breakages seen in the genus.[24]

Paleoecology

Machairodus seemed to prefer open woodland habitat, as evidenced by finds at Cerro de los Batallones, which is of Vallesian age. As a top predator at Batallones, it would have hunted large herbivores of the time. Such herbivores would have included horses like Hipparion, the hornless rhinoceros Aceratherium, the giraffes Decennatherium and Birgerbohlinia, the deer Euprox and Lucentia, the antelopes Paleoreas, Tragoportax, Miotragocerus and Dorcatherium, the “gomphotherid” elephantoid Tetralophodon, the porcupine Hystrix, and the suid Microstonyx. Machairodus would have competed for such prey with the Amphicyonid Magericyon, fellow machairodonts Promegantereon and Paramachairodus, bears such as Agriotherium and Indarctos, and the small hyaenid Protictitherium. While Agriotherium and Magericyon would likely have been strongly competitive with Machairodus for food, Promegantereon, Paramachairodus and Protictitherium likely were less potential rivals.[25] Evidence also exists indicating that Machairodus may have been prone to niche partitioning with Magericyon, possibly living in slightly different habitats, with the machairodont preferring more heavily vegetated habitats while the bear-dog hunted in the more open areas. Dietary preferences may also have played a role in the coexistence between these two large predators at Batallones.[26]

Based on its jaw gape, the largest species, M. horribilis was probably a hunter of relatively slow-moving horses of the genus Hipparion.[27] It would have also lived alongside the large pig Kubanochoerus. M. lahayishupup would have most likely preyed on the large animals that it lived alongside, which included rhinoceroses, and Hemiauchenia.[28][29]

Pathology

Machairodus aphanistus fossils recovered from Batallones reveal a high percentage of tooth breakages, indicating that unlike later machairodonts, due to a lack of protruding incisors Machairodus often used its sabers to subdue prey in a manner similar to modern cats; this was a more risky strategy that virtually ensured that damage to their saber teeth often occurred.[30]

References

  1. ↑ "PBDB". https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=41059&is_real_user=1. 
  2. ↑ 2.0 2.1 Antón (2013).
  3. ↑ Roberts, George (1839) (in English). An etymological and explanatory dictionary of the terms and language of geology. London: Longman, Orme, Brown, Green, & Longmans. p. 103. https://archive.org/details/anetymologicala00robegoog. Retrieved 31 December 2021. 
  4. ↑ Antón (2013), pp. 118–119.
  5. ↑ J.A. Orlov (1936). "Tertiäre Raubtiere des westlichen Siberiens. I. Machairodontinae, Trav. Inst. Paléozool" (in German). Acad. Sci. URSS 5: 111–152. https://books.google.com/books?id=JEHWEAAAQBAJ&pg=PA111. 
  6. ↑ Kurtén, B. (1976). "Fossil Carnivora from the Late Tertiary of Bled Douarah and Cherichira, Tunisia". Notes du Service Géologique de Tunisie 42: 177–214. 
  7. ↑ Beaumont, G. de (1978). "Notes complementaires sur quelques fe´lide´s (Carnivores)". Archives des Sciences, Gene've 31: 219–27. 
  8. ↑ Lungu, A. N. (1978). "The Hipparion fauna of the middle Sarmatian of Moldavia (carnivorous mammals)" (in Russian). Izd. Shtiintsa, Kishinev: 132. 
  9. ↑ Ginsburg, L.; Morales, J.; Soria, D. (1981). "Nuevos datos sobre los carnívoros de los Valles de Fuentidueña (Segovia)" (in Spanish). Estud Geol 37: 383–415. 
  10. ↑ Fernández-Monescillo, Marcos; Antón, Mauricio; Salesa, Manuel J. (2019). "Palaeoecological implications of the sympatric distribution of two species of Machairodus (Felidae, Machairodontinae, Homotherini) in the Late Miocene of los Valles de Fuentidueña (Segovia, Spain)". Historical Biology 31 (7): 903–913. doi:10.1080/08912963.2017.1402894. 
  11. ↑ Sotnikova, M. V. (1991). "A new species of Machairodus from the late Miocene Kalmakpai locality in eastern Kazakhstan (USSR)". Annales Zoologici Fennici 28 (3/4): 361–369. 
  12. ↑ Turner, Alan (1997). The Big Cats and their fossil relatives. Columbia University Press. pp. 45. ISBN 9780231102292. https://archive.org/details/bigcatstheirfoss00turn. 
  13. ↑ Fernandez-Monescillo, Marcos; Anton, Mauricio; Salesa, Manuel.J (2017). "Alaeoecological implications of the sympatric distribution of two species ofMachairodus (Felidae, Machairodontinae, Homotherini) in the Late Miocene of Los Valles de Fuentidueña (Segovia, Spain)". Historical Biology 31 (7): 903–913. doi:10.1080/08912963.2017.1402894. 
  14. ↑ Giovanni G. Bellani (2019). Felines of the World. Discoveries in Taxonomic Classification and History. Elsevier Science. pp. 31. ISBN 9780128172773. https://books.google.com/books?id=xK2wDwAAQBAJ. Retrieved 19 September 2022. 
  15. ↑ 15.0 15.1 Switek, Brian (November 3, 2016). "The Biggest Saber Cat". https://blogs.scientificamerican.com/laelaps/the-biggest-saber-cat/. 
  16. ↑ Sokol, Joshua (14 March 2020). "They Knew Saber-Toothed Tigers Were Big. Then They Found This Skull". The New York Times. https://www.nytimes.com/2020/03/14/science/saber-toothed-tiger.html?referringSource=articleShare. 
  17. ↑ "Newly identified saber-toothed cat is one of largest in history". https://phys.org/news/2021-05-newly-saber-toothed-cat-largest-history.html. 
  18. ↑ Orcutt, John D.; Calede, Jonathan J.M. (2021). "Quantitative Analyses of Feliform Humeri Reveal the Existence of a Very Large Cat in North America During the Miocene". Journal of Mammalian Evolution 28 (3): 729–751. doi:10.1007/s10914-021-09540-1. https://link.springer.com/article/10.1007/s10914-021-09540-1. 
  19. ↑ Lazaro, Enrico de (4 May 2021). "Giant Saber-Toothed Cat Roamed North America during Miocene | Paleontology | Sci-News.com". https://www.sci.news/paleontology/machairodus-lahayishupup-09619.html. Retrieved 18 December 2022. 
  20. ↑ Deng, Tao; Zhang, Yun-Xiang. "A skull of Machairodus horribilis and new evidence for gigantism as a mode of mosaic evolution in machairodonts (Felidae, Carnivora)". Vertebrata PalAsiatica 54: 302–318. https://www.researchgate.net/publication/309409331. 
  21. ↑ Legendre, S.; Roth, C. (1988). "Correlation of carnassial tooth size and body weight in recent carnivores (Mammalia)". Historical Biology 1 (1): 85–98. doi:10.1080/08912968809386468. 
  22. ↑ 22.0 22.1 Turner, Alan (1997). The Big Cats and Their Fossil Relatives. Illustrated by Mauricio Antón. Columbia University Press. pp. 233. ISBN 978-0-231-10228-5. https://books.google.com/books?id=66mRJSxIAfoC. 
  23. ↑ Antón, Mauricio; Salesa, Manuel J.; Siliceo, Gema (2013). "Machairodont adaptations and affinities of the Holarctic late Miocene homotherin Machairodus(Mammalia, Carnivora, Felidae): the case of Machairodus catocopis Cope, 1887". Journal of Vertebrate Paleontology 33 (5): 1202–1213. doi:10.1080/02724634.2013.760468. ISSN 0272-4634. Bibcode: 2013JVPal..33.1202A. 
  24. ↑ Antón, Mauricio; Siliceo, Gema; Pastor, Juan Francisco; Morales, Jorge; Salesa, Manuel J. (2020). "The early evolution of the sabre-toothed felid killing bite: The significance of the cervical morphology of Machairodus aphanistus (Carnivora: Felidae: Machairodontinae)". Zoological Journal of the Linnean Society 188: 319–342. doi:10.1093/zoolinnean/zlz086. https://academic.oup.com/zoolinnean/article-abstract/188/1/319/5581941?redirectedFrom=fulltext. 
  25. ↑ Antón (2013), p. 52.
  26. ↑ Switek, Brian (November 30, 2012). "Carnivorous Neighbors — How Sabercats and a Bear Dog Managed to Coexist". National Geographic. http://phenomena.nationalgeographic.com/2012/11/30/carnivorous-neighbors-how-sabercats-and-a-bear-dog-managed-to-coexist/. 
  27. ↑ Weisberger, Mindy (November 7, 2016). "Saber-Toothed Cat Had a Huge Skull, But a Puny Bite". http://www.livescience.com/56775-sabertooth-cat-bite-diversity.html. 
  28. ↑ Marie Morales (May 5, 2021). "Sabre-Toothed Cat From 9 Million Years Ago Could Take Down Prey 10 Times Its Size". The Science Times. https://www.sciencetimes.com/articles/31013/20210505/sabre-toothed-cat-from-9-million-years-ago-could-take-down-prey-ten-times-its-size.htm. Retrieved May 9, 2021. 
  29. ↑ David Nield (8 May 2021). "Newly Identified Species of Saber-Toothed Cat Was So Big It Hunted Rhinos in America". ScienceAlert. https://www.sciencealert.com/scientists-identify-a-giant-saber-toothed-cat-that-prowled-the-us-5-9-million-years-ago. Retrieved 9 May 2021. 
  30. ↑ Antón (2013), pp. 183–184.
  • Antón, Mauricio (2013). Sabertooth. Bloomington, Indiana: University of Indiana Press. ISBN 9780253010421. 

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