Mesotherium
Encyclopedia
Mesotherium
better known by its synonym, "Typotherium," is the type genus
of Mesotheriidae
, a long-lasting (roughly from 55 to 2 mya) family
of superficially rodent-like, burrowing notoungulates from South America. It was first named by Étienne Serres
in 1867, and through further finds now contains four species, M. cristatum, M. hystatum, M. maendrum, and M. pachygnathum.
wrote Darwin in April 1863. "Bravard sent it home under the name of Typotherium as being the central type from which all mammals diverged." It was Serres' view that there was only one underlying animal type.
Despite Serres' having officially named the genus Mesotherium, it was known from the late 19th century to the early 20th century under the name "Typotherium", given it by the French palaeontologist living in Argentina, Auguste Bravard
; under this name Bravard sent the skull he found to Paris, which led to the family being named Typotheriidae, and served as the basis for the order Typotheria. As the name "Mesotherium" had been published earlier in the same year as "Typotherium", Mesotherium was declared the valid name of the genus, (Simpson, 1980) and Mesotheriidae the valid name of the family. Nevertheless, as the rules do not apply to anything above the family, the name of the order Typotheria is still in use, but refers to a wider range of rodent-like notoungulates.
and lingual
surfaces of the incisors, while rodents only have enamel on the labial surface. Mesotheriums lower incisors were reminiscent of those of a rabbit
's.
Mesotheriums ankle joint was made up of a "ball-and-socket" arrangement between the astralagus
and the navicular, as well as a sliding articulation of the calcaneocuboid joint, which would cause extension-flexion in the ankle, as well as supination-pronation of the foot. Because of this, Florentino Ameghino
predicted in 1905, and confirmed in 1906 that Mesotherium would have a great toe.
Mesotherium was likely fossorial
, in that it dug, possibly to find food.
better known by its synonym, "Typotherium," is the type genus
Type genus
In biological classification, a type genus is a representative genus, as with regard to a biological family. The term and concept is used much more often and much more formally in zoology than it is in botany, and the definition is dependent on the nomenclatural Code that applies:* In zoological...
of Mesotheriidae
Mesotheriidae
Mesotheriidae is an extinct family of notoungulate mammals known from the Eocene through the Pleistocene of South America. Mesotheriids were small to medium-sized herbivorous mammals adapted for digging.-Characteristics:...
, a long-lasting (roughly from 55 to 2 mya) family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
of superficially rodent-like, burrowing notoungulates from South America. It was first named by Étienne Serres
Étienne Serres
Antoine Étienne Renaud Augustin Serres was a French physician and embryologist.In 1810 Serres received his medical doctorate in Paris, and afterwards worked at the Hôtel-Dieu de Paris and the Hôpital de la Pitié. Beginning in 1839 he taught comparative anatomy at the Jardin des Plantes. In 1841 he...
in 1867, and through further finds now contains four species, M. cristatum, M. hystatum, M. maendrum, and M. pachygnathum.
Etymology
Serres named Mesotherium so due to his belief that it was an intermediate between rodents and pachyderms (or ungulates), due to its large upper incisors, and its size and proportions. "Serres—by a happy inspiration proposed calling it Mesotherium—as being a common centre towards which all mammalia got happily confounded," Hugh FalconerHugh Falconer
Hugh Falconer MD FRS was a Scottish geologist, botanist, palaeontologist and paleoanthropologist. He studied the flora, fauna and geology of India, Assam and Burma, and was the first to suggest the modern evolutionary theory of punctuated equilibrium...
wrote Darwin in April 1863. "Bravard sent it home under the name of Typotherium as being the central type from which all mammals diverged." It was Serres' view that there was only one underlying animal type.
Despite Serres' having officially named the genus Mesotherium, it was known from the late 19th century to the early 20th century under the name "Typotherium", given it by the French palaeontologist living in Argentina, Auguste Bravard
Auguste Bravard
Auguste Bravard was a French mining engineer turned palaeontologist who, having hunted fossils in the Vaucluse, Allier and his native Puy de Dôme emigrated to Argentina in the winter of 1852-53 and was a long-term resident in Buenos Aires, where he unearthed and studied mammalian fossils, some of...
; under this name Bravard sent the skull he found to Paris, which led to the family being named Typotheriidae, and served as the basis for the order Typotheria. As the name "Mesotherium" had been published earlier in the same year as "Typotherium", Mesotherium was declared the valid name of the genus, (Simpson, 1980) and Mesotheriidae the valid name of the family. Nevertheless, as the rules do not apply to anything above the family, the name of the order Typotheria is still in use, but refers to a wider range of rodent-like notoungulates.
Description
Mesotherium was likely the size of a small sheep, and weighed around 55 kilograms (121.3 lb). Like most rodents, it had superficially long upper incisors, which met at the tips, however, it had enamel on both the labialLip
Lips are a visible body part at the mouth of humans and many animals. Lips are soft, movable, and serve as the opening for food intake and in the articulation of sound and speech...
and lingual
Tongue
The tongue is a muscular hydrostat on the floors of the mouths of most vertebrates which manipulates food for mastication. It is the primary organ of taste , as much of the upper surface of the tongue is covered in papillae and taste buds. It is sensitive and kept moist by saliva, and is richly...
surfaces of the incisors, while rodents only have enamel on the labial surface. Mesotheriums lower incisors were reminiscent of those of a rabbit
Rabbit
Rabbits are small mammals in the family Leporidae of the order Lagomorpha, found in several parts of the world...
's.
Mesotheriums ankle joint was made up of a "ball-and-socket" arrangement between the astralagus
Talus bone
-External links:* *...
and the navicular, as well as a sliding articulation of the calcaneocuboid joint, which would cause extension-flexion in the ankle, as well as supination-pronation of the foot. Because of this, Florentino Ameghino
Florentino Ameghino
Florentino Ameghino was an Argentine naturalist, paleontologist, anthropologist and zoologist.Born in Luján, son of Italian immigrants, Ameghino was a self-taught naturalist, and focused his study on the lands of the southern Pampas...
predicted in 1905, and confirmed in 1906 that Mesotherium would have a great toe.
Mesotherium was likely fossorial
Fossorial
A fossorial organism is one that is adapted to digging and life underground such as the badger, the naked mole rat, and the mole salamanders Ambystomatidae...
, in that it dug, possibly to find food.
Further reading
- The Origin and Evolution of Mammals (Oxford Biology) by T. S. Kemp
- Horns, Tusks, and Flippers: The Evolution of Hoofed Mammals By Donald R. Prothero, Robert M. Schoch Published 2003 JHU Press ISBN 0801871352
- Forms of Animal Life: A Manual of Comparative Anatomy By George Rolleston, William Hatchett Jackson Published 1888 Clarendon Press
- The Century Dictionary: An Encyclopedic Lexicon of the English Language By William Dwight Whitney. Published 1890 The Century CompanyThe Century CompanyThe Century Company was an American publishing company, founded in 1881.It was originally a subsidiary of Charles Scribner's Sons, but was bought and renamed. The magazine it had published up to that time, Scribners Monthly, was renamed The Century Illustrated Monthly Magazine.The Century Company...
; original from Harvard UniversityHarvard UniversityHarvard University is a private Ivy League university located in Cambridge, Massachusetts, United States, established in 1636 by the Massachusetts legislature. Harvard is the oldest institution of higher learning in the United States and the first corporation chartered in the country...
. - Classification of Mammals Above the Species Level: Above the Species Level By Malcolm C. McKenna, Susan K. Bell, George Gaylord Simpson. Published 1997 Columbia University PressColumbia University PressColumbia University Press is a university press based in New York City, and affiliated with Columbia University. It is currently directed by James D. Jordan and publishes titles in the humanities and sciences, including the fields of literary and cultural studies, history, social work, sociology,...
. ISBN 0231110138 - Neanderthals Revisited: New Approaches and Perspectives By Katerina Harvati, Terry Harrison. Publisher SpringerSpringer Science+Business Media- Selected publications :* Encyclopaedia of Mathematics* Ergebnisse der Mathematik und ihrer Grenzgebiete * Graduate Texts in Mathematics * Grothendieck's Séminaire de géométrie algébrique...
ISBN 1402058446
External links
- Mesotherium in the Paleobiology DatabasePaleobiology Database' is an online resource for information on the distribution and classification of fossil animals, plants, and microorganisms.-History:The Paleobiology Database was founded in 2000. It has been funded by the National Science Foundation and the Australian Research Council...
- Reconstructed image of Mesotherium head
- New Mesotheriidae (Mammalia, Notoungulata, Typotheria),geochronology and tectonics of the Caragua area, northernmost Chile