Post by Infinity Blade on Nov 23, 2021 5:31:02 GMT 5
Elasmotherium spp.
© @ Julio Lacerda
Temporal range: Neogene to Quaternary; Late Miocene[1] to Pleistocene; (extinct by ~39 ka[2])
Scientific classification:
Domain: Eukaryota
(unranked): Unikonta
(unranked): Opisthokonta
(unranked): Holozoa
(unranked): Filozoa
Kingdom: Animalia
Subkingdom: Eumetazoa
(unranked): Bilateria
Superphylum: Deuterostomia
Phylum: Chordata
Infraphylum: Gnathostomata
Clade: Eugnathostomata
Clade: Teleostomi
Superclass: Tetrapoda
Clade: Reptiliomorpha
Clade: Amniota
Clade: Synapsida
Clade: Eupelycosauria
Clade: Sphenacodontia
Clade: Sphenacodontoidea
Order: Therapsida
Suborder: Cynodontia
Clade: Prozostrodontia
Clade: Mammaliaformes
Class: Mammalia
Legion: Cladotheria
Sublegion: Zatheria
Infralegion: Tribosphenida
Subclass: Theria
Clade: Eutheria
Infraclass: Placentalia
Subcohort: Exafroplacentalia
Magnorder: Boreoeutheria
Superorder: Laurasiatheria
Clade: Ungulata
Order: Perissodactyla
Suborder: Ceratomorpha
Superfamily: Rhinocerotoidea
Family: Rhinocerotidae
Subfamily: †Elasmotheriinae
Genus: †Elasmotherium
Species: †E. sibiricum (type species)
†E. caucasicum
†E. chaprovicum? (possibly synonymous with E. peii)[1]
†E. peii
†E. primigenium
Elasmotherium (“laminated beast”) is an extinct genus of rhinoceros that lived across Eurasia from the late Miocene to the late Pleistocene, going extinct around 39-35 ka.[2]
Evolution:
Elasmotheriines diverged from all other rhinocerotids long ago, presumably in the early Oligocene or even the Eocene (30-40 million years ago).[3] The earliest known elasmothere from the fossil record is Bugtirhinus praecursor, which lived in South Asia during the early Miocene. Elasmotherium itself is believed to have evolved from the genus Sinotherium, due to the fact that it is the closest to Elasmotherium in dental morphology.[1]
The “horns” of elasmotheres shifted in position throughout the subfamily’s evolution. Early elasmotheres had keratinous/keratoid structures above their noses, while later elasmotheres (like Elasmotherium itself) had these keratoid structures on their frontal bones. Sinotherium lagrelii had a huge nasofrontal boss and a much smaller frontal boss behind it, and thus is a transitional form between elasmotheres with a nasal “horn”/boss and elasmotheres with a frontal boss.[4]
The first species of Elasmotherium appeared in the late Miocene of northern China. E. primigenium had a huge frontal boss and no nasofrontal boss, making it transitional between Sinotherium and more derived species of Elasmotherium. It is distinguished from other Elasmotherium species by several diagnostic features, including slightly wrinkled enamel (compared to other species).[1]
Fig. 3 of Deng et al. (2013), showing the evolution of the shift from nasal to frontal structures in elasmotheres. Keep in mind the unlikely massive horn reconstructions on the more derived elasmotheres.
Description:
Elasmotherium was a large rhinoceros. E. sibiricum has been estimated to weigh ~3.5 to >4 tonnes[2][5][6], while E. caucasicum has been estimated to weigh as much as >5 tonnes.[6] The limb bones of E. caucasicum were slender distally and show evidence of cursoriality and dwelling in an open steppe.[7] However, E. sibiricum had a particularly robust calcaneus, even compared to the larger Paraceratherium (which had a thinner and more elongated calcaneus than expected for a perissodactyl of its body mass), and rhinocerotids in general possess moderately deep trochlea. Since Elasmotherium was one of the heaviest rhinocerotids, it presumably had a relatively flatter trochlea compared to most other family members. A deeper trochlea provides more stability for the crurotarsal joint, but also has thinner and more fragile ridges, unable to take extremely high forces on the ankle. This same flattening is observed in brontotheres, elephants, and sauropod dinosaurs. A short, robust calcaneus and flat trochlea of the astragalus (with a lack of ridges) are both characteristic of highly graviportal animals.[8] This may have implications for the gait of Elasmotherium; if it had more columnar, rigid ankles[9], this would be inconsistent with cursorial locomotion and a galloping gait seen in modern rhinos.
Elasmotherium has long been popularly depicted with a single long, massive horn on top of its head, sometimes earning it the name “Siberian unicorn”.[5] But recently, an examination of the huge frontal dome of Elasmotherium suggested that in life, the “horn” was actually a short keratoid pad. This is based on the distinct texture on the surface of the dome (different from what is seen in modern rhinos, and more comparable to what is seen on the bosses of muskoxen and cape buffalo) and the thin bone walls of the hollow dome. The dome would have functioned to enhance olfaction and perhaps even amplify sounds; the relatively thin keratoid pad would provide passive protection for this fragile bony structure.[3]
Fig. 6 of [3].
Elasmotherium also possessed a solid internasal septum, something shared with the woolly rhinoceros (Coelodonta antiquitatis) but not modern rhinos (which have a cartilaginous nasal septum). This indicated substantial loads of force were exerted onto it. Indeed, Elasmotherium possessed visible, rough thickenings at the anterior end of its nasal and intermaxillary bones. This suggests the presence of a small horn-like cornified pad, which would have functioned to loosen and dig up soil for food. Indeed, the neck musculature of Elasmotherium emphasized powerful lateral and dorsolateral movements.[3]
Modern rhinos that use their horns as weapons have a supraoccipital region stretched upward and backward to elongate the power arm of the entire lever system consisting of their muzzle, occipital condyles, and supraoccipital crest. Also, their horns are shifted forwards (i.e. on the nose) to best utilize all the impulsion given by the neck muscles. By contrast, the skull of Elasmotherium is characterized by a vertical occiput and moderately backwards projected supraoccipital crests. This, coupled with the position of the “horn” on the frontal, made the “horn” unsuitable for fights.[10]
Diet:
Elasmotherium had enormous, continuously growing, rootless, hypsodont cheek teeth. This is an adaptation to feeding on highly abrasive food items. The dental morphology and the angle of its head and neck also point towards an animal that fed close to the ground or even eating underground plant bulbs and roots. Carbon and nitrogen isotopes of Elasmotherium sibiricum overlap considerably with those of Late Pleistocene saiga antelope remains from the mammoth steppe, and indicate a very specialized diet, including underground plant parts.[11] Elasmotherium remains from Irgiz 1 suggest the animals would shift from a grazing to a browsing diet when their typical food was unavailable, but would die if poor conditions persisted and food remained unavailable.[12]
Another study corroborated an extremely specialized diet in Elasmotherium. It notes that the obtuse angle between the plane of the occiput and the palate suggests it held its head even lower than the woolly and white rhinos. The stable isotope analysis found a clearly distinct diet from other rhinoceros species, being high in both nitrogen and carbon isotopes. As with previous work[11], Elasmotherium strongly overlapped with contemporary saiga antelope.[13]
Extinction:
Elasmotherium likely went extinct ~39-35 thousand years ago. The timing of its extinction is coincident with that of Homo neanderthalensis and the stilt-legged horse Haringtonhippus francisci, as well as a major episode of ice rafting into the North Atlantic (Greenland Stadial 3 and Heinrich stadial 4).[2]
Both the saiga antelope and the woolly rhinoceros outlived Elasmotherium. The woolly rhinoceros had a distinct diet from Elasmotherium, while pre-Late Glacial Maximum saiga antelope overlapped considerably with Elasmotherium in diet. However, saiga samples from other periods and other areas had lower nitrogen isotope values, indicating the saiga has a flexible diet. Elasmotherium, by contrast, was a highly specialized grazer. It inhabited dry steppe habitats and forest-steppe areas with extensive grass. The specialized diet of Elasmotherium, along with its restricted geographical range (a result of its specialized habitat), low population size, and slow reproductive rate (associated with large body size), would have made it susceptible to extinction. Human hunting pressure could also have contributed to Elasmotherium’s extinction, although there is presently no evidence of human hunting of the species.[2]
References:
[1] Sun, D., Deng, T., & Jiangzuo, Q. (2021). The most primitive Elasmotherium (Perissodactyla, Rhinocerotidae) from the Late Miocene of northern China. Historical Biology, 1-11.
[2] Kosintsev, P., Mitchell, K. J., Devièse, T., van der Plicht, J., Kuitems, M., Petrova, E., ... & Lister, A. M. (2019). Evolution and extinction of the giant rhinoceros Elasmotherium sibiricum sheds light on late Quaternary megafaunal extinctions. Nature ecology & evolution, 3(1), 31-38.
[3] Titov, V. V., Baigusheva, V. S., & Uchytel, R. S. (2021). The experience in reconstructing of the head of Elasmotherium (Rhinocerotidae).
[4] Deng, T., Wang, S., & Hou, S. (2013). A bizarre tandem-horned elasmothere rhino from the Late Miocene of northwestern China and origin of the true elasmothere. Chinese Science Bulletin, 58(15), 1811-1817.
[5] Stuart, A. J. (2021). Vanished Giants: The Lost World of the Ice Age. University of Chicago Press. p. 40.
[6] Cerdeño, E. (1998). Diversity and evolutionary trends of the Family Rhinocerotidae (Perissodactyla). Palaeogeography, Palaeoclimatology, Palaeoecology, 141(1-2), 13-34.
[7] Tao, D., & Min, Z. (2005). LIMB BONES OF ELASMOTHERIUM (RHINOCEROTIDAE, PERISSODACTYLA) FROM NIHEWAN (HEBEI, CHINA). Vertebrata Palasiatica, 43(02), 110.
[8] Etienne, C., Mallet, C., Cornette, R., & Houssaye, A. (2020). Influence of mass on tarsus shape variation: a morphometrical investigation among Rhinocerotidae (Mammalia: Perissodactyla). Biological Journal of the Linnean Society, 129(4), 950-974.
[9] Harrison, N. (2019). The Origins of Europeans and Their Pre-Historic Innovations from 6 Million to 10,000 BCE: From 6 Million to 10,000 BCE. Algora Publishing. p. 236.
[10] Mazza, P., Azzaroli, A. Ethological inferences on Pleistocene rhinoceroses of Europe. Rend. Fis. Acc. Lincei 4, 127 (1993). doi.org/10.1007/BF03001424
[11] Kuitems, M. (2020). Analysis of 13C and 15N isotopes from Eurasian Quaternary fossils: Insights in diet, climate and ecology (Doctoral dissertation, Leiden University).
[12] Rivals, F., Prilepskaya, N. E., Belyaev, R. I., & Pervushov, E. M. (2020). Dramatic change in the diet of a late Pleistocene Elasmotherium population during its last days of life: Implications for its catastrophic mortality in the Saratov region of Russia. Palaeogeography, Palaeoclimatology, Palaeoecology, 556, 109898.
© @ Julio Lacerda
Temporal range: Neogene to Quaternary; Late Miocene[1] to Pleistocene; (extinct by ~39 ka[2])
Scientific classification:
Domain: Eukaryota
(unranked): Unikonta
(unranked): Opisthokonta
(unranked): Holozoa
(unranked): Filozoa
Kingdom: Animalia
Subkingdom: Eumetazoa
(unranked): Bilateria
Superphylum: Deuterostomia
Phylum: Chordata
Infraphylum: Gnathostomata
Clade: Eugnathostomata
Clade: Teleostomi
Superclass: Tetrapoda
Clade: Reptiliomorpha
Clade: Amniota
Clade: Synapsida
Clade: Eupelycosauria
Clade: Sphenacodontia
Clade: Sphenacodontoidea
Order: Therapsida
Suborder: Cynodontia
Clade: Prozostrodontia
Clade: Mammaliaformes
Class: Mammalia
Legion: Cladotheria
Sublegion: Zatheria
Infralegion: Tribosphenida
Subclass: Theria
Clade: Eutheria
Infraclass: Placentalia
Subcohort: Exafroplacentalia
Magnorder: Boreoeutheria
Superorder: Laurasiatheria
Clade: Ungulata
Order: Perissodactyla
Suborder: Ceratomorpha
Superfamily: Rhinocerotoidea
Family: Rhinocerotidae
Subfamily: †Elasmotheriinae
Genus: †Elasmotherium
Species: †E. sibiricum (type species)
†E. caucasicum
†E. chaprovicum? (possibly synonymous with E. peii)[1]
†E. peii
†E. primigenium
Elasmotherium (“laminated beast”) is an extinct genus of rhinoceros that lived across Eurasia from the late Miocene to the late Pleistocene, going extinct around 39-35 ka.[2]
Evolution:
Elasmotheriines diverged from all other rhinocerotids long ago, presumably in the early Oligocene or even the Eocene (30-40 million years ago).[3] The earliest known elasmothere from the fossil record is Bugtirhinus praecursor, which lived in South Asia during the early Miocene. Elasmotherium itself is believed to have evolved from the genus Sinotherium, due to the fact that it is the closest to Elasmotherium in dental morphology.[1]
The “horns” of elasmotheres shifted in position throughout the subfamily’s evolution. Early elasmotheres had keratinous/keratoid structures above their noses, while later elasmotheres (like Elasmotherium itself) had these keratoid structures on their frontal bones. Sinotherium lagrelii had a huge nasofrontal boss and a much smaller frontal boss behind it, and thus is a transitional form between elasmotheres with a nasal “horn”/boss and elasmotheres with a frontal boss.[4]
The first species of Elasmotherium appeared in the late Miocene of northern China. E. primigenium had a huge frontal boss and no nasofrontal boss, making it transitional between Sinotherium and more derived species of Elasmotherium. It is distinguished from other Elasmotherium species by several diagnostic features, including slightly wrinkled enamel (compared to other species).[1]
Fig. 3 of Deng et al. (2013), showing the evolution of the shift from nasal to frontal structures in elasmotheres. Keep in mind the unlikely massive horn reconstructions on the more derived elasmotheres.
Description:
Elasmotherium was a large rhinoceros. E. sibiricum has been estimated to weigh ~3.5 to >4 tonnes[2][5][6], while E. caucasicum has been estimated to weigh as much as >5 tonnes.[6] The limb bones of E. caucasicum were slender distally and show evidence of cursoriality and dwelling in an open steppe.[7] However, E. sibiricum had a particularly robust calcaneus, even compared to the larger Paraceratherium (which had a thinner and more elongated calcaneus than expected for a perissodactyl of its body mass), and rhinocerotids in general possess moderately deep trochlea. Since Elasmotherium was one of the heaviest rhinocerotids, it presumably had a relatively flatter trochlea compared to most other family members. A deeper trochlea provides more stability for the crurotarsal joint, but also has thinner and more fragile ridges, unable to take extremely high forces on the ankle. This same flattening is observed in brontotheres, elephants, and sauropod dinosaurs. A short, robust calcaneus and flat trochlea of the astragalus (with a lack of ridges) are both characteristic of highly graviportal animals.[8] This may have implications for the gait of Elasmotherium; if it had more columnar, rigid ankles[9], this would be inconsistent with cursorial locomotion and a galloping gait seen in modern rhinos.
Elasmotherium has long been popularly depicted with a single long, massive horn on top of its head, sometimes earning it the name “Siberian unicorn”.[5] But recently, an examination of the huge frontal dome of Elasmotherium suggested that in life, the “horn” was actually a short keratoid pad. This is based on the distinct texture on the surface of the dome (different from what is seen in modern rhinos, and more comparable to what is seen on the bosses of muskoxen and cape buffalo) and the thin bone walls of the hollow dome. The dome would have functioned to enhance olfaction and perhaps even amplify sounds; the relatively thin keratoid pad would provide passive protection for this fragile bony structure.[3]
Fig. 6 of [3].
Elasmotherium also possessed a solid internasal septum, something shared with the woolly rhinoceros (Coelodonta antiquitatis) but not modern rhinos (which have a cartilaginous nasal septum). This indicated substantial loads of force were exerted onto it. Indeed, Elasmotherium possessed visible, rough thickenings at the anterior end of its nasal and intermaxillary bones. This suggests the presence of a small horn-like cornified pad, which would have functioned to loosen and dig up soil for food. Indeed, the neck musculature of Elasmotherium emphasized powerful lateral and dorsolateral movements.[3]
Modern rhinos that use their horns as weapons have a supraoccipital region stretched upward and backward to elongate the power arm of the entire lever system consisting of their muzzle, occipital condyles, and supraoccipital crest. Also, their horns are shifted forwards (i.e. on the nose) to best utilize all the impulsion given by the neck muscles. By contrast, the skull of Elasmotherium is characterized by a vertical occiput and moderately backwards projected supraoccipital crests. This, coupled with the position of the “horn” on the frontal, made the “horn” unsuitable for fights.[10]
Diet:
Elasmotherium had enormous, continuously growing, rootless, hypsodont cheek teeth. This is an adaptation to feeding on highly abrasive food items. The dental morphology and the angle of its head and neck also point towards an animal that fed close to the ground or even eating underground plant bulbs and roots. Carbon and nitrogen isotopes of Elasmotherium sibiricum overlap considerably with those of Late Pleistocene saiga antelope remains from the mammoth steppe, and indicate a very specialized diet, including underground plant parts.[11] Elasmotherium remains from Irgiz 1 suggest the animals would shift from a grazing to a browsing diet when their typical food was unavailable, but would die if poor conditions persisted and food remained unavailable.[12]
Another study corroborated an extremely specialized diet in Elasmotherium. It notes that the obtuse angle between the plane of the occiput and the palate suggests it held its head even lower than the woolly and white rhinos. The stable isotope analysis found a clearly distinct diet from other rhinoceros species, being high in both nitrogen and carbon isotopes. As with previous work[11], Elasmotherium strongly overlapped with contemporary saiga antelope.[13]
Extinction:
Elasmotherium likely went extinct ~39-35 thousand years ago. The timing of its extinction is coincident with that of Homo neanderthalensis and the stilt-legged horse Haringtonhippus francisci, as well as a major episode of ice rafting into the North Atlantic (Greenland Stadial 3 and Heinrich stadial 4).[2]
Both the saiga antelope and the woolly rhinoceros outlived Elasmotherium. The woolly rhinoceros had a distinct diet from Elasmotherium, while pre-Late Glacial Maximum saiga antelope overlapped considerably with Elasmotherium in diet. However, saiga samples from other periods and other areas had lower nitrogen isotope values, indicating the saiga has a flexible diet. Elasmotherium, by contrast, was a highly specialized grazer. It inhabited dry steppe habitats and forest-steppe areas with extensive grass. The specialized diet of Elasmotherium, along with its restricted geographical range (a result of its specialized habitat), low population size, and slow reproductive rate (associated with large body size), would have made it susceptible to extinction. Human hunting pressure could also have contributed to Elasmotherium’s extinction, although there is presently no evidence of human hunting of the species.[2]
References:
[1] Sun, D., Deng, T., & Jiangzuo, Q. (2021). The most primitive Elasmotherium (Perissodactyla, Rhinocerotidae) from the Late Miocene of northern China. Historical Biology, 1-11.
[2] Kosintsev, P., Mitchell, K. J., Devièse, T., van der Plicht, J., Kuitems, M., Petrova, E., ... & Lister, A. M. (2019). Evolution and extinction of the giant rhinoceros Elasmotherium sibiricum sheds light on late Quaternary megafaunal extinctions. Nature ecology & evolution, 3(1), 31-38.
[3] Titov, V. V., Baigusheva, V. S., & Uchytel, R. S. (2021). The experience in reconstructing of the head of Elasmotherium (Rhinocerotidae).
[4] Deng, T., Wang, S., & Hou, S. (2013). A bizarre tandem-horned elasmothere rhino from the Late Miocene of northwestern China and origin of the true elasmothere. Chinese Science Bulletin, 58(15), 1811-1817.
[5] Stuart, A. J. (2021). Vanished Giants: The Lost World of the Ice Age. University of Chicago Press. p. 40.
[6] Cerdeño, E. (1998). Diversity and evolutionary trends of the Family Rhinocerotidae (Perissodactyla). Palaeogeography, Palaeoclimatology, Palaeoecology, 141(1-2), 13-34.
[7] Tao, D., & Min, Z. (2005). LIMB BONES OF ELASMOTHERIUM (RHINOCEROTIDAE, PERISSODACTYLA) FROM NIHEWAN (HEBEI, CHINA). Vertebrata Palasiatica, 43(02), 110.
[8] Etienne, C., Mallet, C., Cornette, R., & Houssaye, A. (2020). Influence of mass on tarsus shape variation: a morphometrical investigation among Rhinocerotidae (Mammalia: Perissodactyla). Biological Journal of the Linnean Society, 129(4), 950-974.
[9] Harrison, N. (2019). The Origins of Europeans and Their Pre-Historic Innovations from 6 Million to 10,000 BCE: From 6 Million to 10,000 BCE. Algora Publishing. p. 236.
[10] Mazza, P., Azzaroli, A. Ethological inferences on Pleistocene rhinoceroses of Europe. Rend. Fis. Acc. Lincei 4, 127 (1993). doi.org/10.1007/BF03001424
[11] Kuitems, M. (2020). Analysis of 13C and 15N isotopes from Eurasian Quaternary fossils: Insights in diet, climate and ecology (Doctoral dissertation, Leiden University).
[12] Rivals, F., Prilepskaya, N. E., Belyaev, R. I., & Pervushov, E. M. (2020). Dramatic change in the diet of a late Pleistocene Elasmotherium population during its last days of life: Implications for its catastrophic mortality in the Saratov region of Russia. Palaeogeography, Palaeoclimatology, Palaeoecology, 556, 109898.
