Eotheroides is an extinct genus of Eocenesirenian. It is an early member of the family Dugongidae, which includes the extant dugong. Fossils have been found from Egypt, India, and Madagascar. Eotheroides was first described by Richard Owen in 1875 under the name Eotherium, which was replaced by the current name in 1899.
Based on endocranial casts, Eotheroiodes had a smaller endocranial volume than other contemporaneous sirenians such as Protosiren. Unlike extant sirenians, Eotheroides possesses a tentorium cerebelli, which appears as a distinct transverse groove on the skull.[1]
The type species, E. aegyptiacum, is known from the Lutetian Mokattam Limestone of Cairo, Egypt.[1] Another species, E. lambondrano, was recently[when?] named on the basis of material found from Middle Eocene nearshore marine deposits in the Mahajanga Basin of Madagascar. The species was named after the Malagasy word for dugong, which translates as "water bushpig". It is known from a nearly complete skull and fragments of pachyosteosclerotic (thick) ribs. Based on its age and morphology, E. lambondrano may be ancestral to E. aegyptiacum.[2] Described in 2009, E. lambondrano is the first pre-PleistoceneCenozoic mammal named from Madagascar, being known from an 80-million-year gap in the island's fossil record.[3]
Several other species have been named, including E. babiae from India,[4]E. majus, E. clavigerum and E. sandersi from Egypt,[5][6] and E. waghapadarensis, also from India.[7]E. majus was based on a single upper molar, which was never catalogued and is now lost;[6] it has been considered a senior subjective synonym of E. aegyptiacum.[8]
Paleobiologyedit
Drawing of swimming Eotheroides sandersi (green), compared to three other Eocene sirenian taxa.
The teeth of Eotheroides were relatively unspecialized compared to those of extant sirenians, which are reduced as an adaptation for feeding on sea grass. The upper molars of E. lambondrano are considerably longer and wider than those of E. aegyptiacum, suggesting that they were less specialized.[1]Eotheroides is likely to have been one of the first fully aquatic sea cows. Eotheroides lambondrano was found in association with the remains of other sea cows, crocodilians, and sea turtles, which suggests that the locality is representative of a coastal or estuarine environment.[3]
Referencesedit
^ abcGingerich, P. D.; Domning, D. P.; Blane, C. E.; Uhen, M. D. (1994). "Late Eocene sea cows (Mammalia, Sirenia) from Wadi Al Hitan in the Fayum Basin, Egypt". Contributions from the Museum of Paleontology. 29 (2). University of Michigan: 41–67.
^Samonds, K. E.; Zalmout, I. S.; Irwin, M. T.; Krause, D. W.; Rogers, R. R.; Raharivony, L. L. (2009). "Eotheroides lambondrano, new Middle Eocene seacow (Mammalia, Sirenia) from the Mahajanga Basin, Northwestern Madagascar". Journal of Vertebrate Paleontology. 29 (4): 1233–1243. Bibcode:2009JVPal..29.1233S. doi:10.1671/039.029.0417. S2CID 59466434.
^ ab"Ancient Pygmy Sea Cow Discovered". Science Daily. 18 December 2009. Retrieved 18 December 2009.
^Bajpai, S.; Thewissen, J. G. M.; Kapur, V. V.; Tiwari, B. N.; Sahni, A. (2006). "Eocene and Oligocene sirenians (Mammalia) from Kachchh, India". Journal of Vertebrate Paleontology. 26 (2): 400–410. doi:10.1671/0272-4634(2006)26[400:eaosmf]2.0.co;2. S2CID 86682899.
^Zdansky, O. (1138). "Eotherium majus sp. n., eine neue Sirene aus dem Mitteleozän von Ägypten". Palaeobiologica. 6: 429–434.
^ abIyad S. Zalmout and Philip D. Gingerich (2012). "Late Eocene Sea Cows (Mammalia, Sirenia) From Wadi Al Hitan In The Western Desert of Fayum, Egypt". University of Michigan Papers on Paleontology. 37: 1–158. hdl:2027.42/94568.
^Das, D. P.; Basu, P. K. (1994). "Study of Palaeogene marine mammals of Kachchh, Guarat". Geological Survey of India. 127 (2): 5.
^Gingerich, P. D. (1992). "Marine Mammals (Cetacean and Sirenia) from the Eocene of Gebel Mokattam and Fayum, Egypt: Stratigraphy, Age, and Paleoenvironments". Contributions from the Museum of Paleontology. 30. University of Michigan: 1–84.
Further readingedit
Marine Mammals: Evolutionary Biology by Annalisa Berta, James L. Sumich, and Kit M. Kovacs
The Beginning of the Age of Mammals by Kenneth D. Rose
Classification of Mammals by Malcolm C. McKenna and Susan K. Bell
eotheroides, extinct, genus, eocene, sirenian, early, member, family, dugongidae, which, includes, extant, dugong, fossils, have, been, found, from, egypt, india, madagascar, first, described, richard, owen, 1875, under, name, eotherium, which, replaced, curre. Eotheroides is an extinct genus of Eocene sirenian It is an early member of the family Dugongidae which includes the extant dugong Fossils have been found from Egypt India and Madagascar Eotheroides was first described by Richard Owen in 1875 under the name Eotherium which was replaced by the current name in 1899 EotheroidesTemporal range Middle Late Eocene 48 6 33 9 Ma PreꞒ Ꞓ O S D C P T J K Pg NEotheroides sp in Artis Amsterdam Scientific classificationKingdom AnimaliaPhylum ChordataClass MammaliaOrder SireniaFamily DugongidaeGenus EotheroidesTrouessart 1905SpeciesE aegyptiacum Owen 1875 type E babiae Bajpai et al 2006 E clavigerum Zalmout and Gingerich 2012 E lambondrano Samonds et al 2009 E majus Zdansky 1938 E sandersi Zalmout and Gingerich 2012 E waghapadarensis Das and Basu 1994Based on endocranial casts Eotheroiodes had a smaller endocranial volume than other contemporaneous sirenians such as Protosiren Unlike extant sirenians Eotheroides possesses a tentorium cerebelli which appears as a distinct transverse groove on the skull 1 Contents 1 Species 2 Paleobiology 3 References 4 Further reading 5 External linksSpecies edit nbsp Drawing of skeleton from the species E sandersiThe type species E aegyptiacum is known from the Lutetian Mokattam Limestone of Cairo Egypt 1 Another species E lambondrano was recently when named on the basis of material found from Middle Eocene nearshore marine deposits in the Mahajanga Basin of Madagascar The species was named after the Malagasy word for dugong which translates as water bushpig It is known from a nearly complete skull and fragments of pachyosteosclerotic thick ribs Based on its age and morphology E lambondrano may be ancestral to E aegyptiacum 2 Described in 2009 E lambondrano is the first pre Pleistocene Cenozoic mammal named from Madagascar being known from an 80 million year gap in the island s fossil record 3 Several other species have been named including E babiae from India 4 E majus E clavigerum and E sandersi from Egypt 5 6 and E waghapadarensis also from India 7 E majus was based on a single upper molar which was never catalogued and is now lost 6 it has been considered a senior subjective synonym of E aegyptiacum 8 Paleobiology edit nbsp Drawing of swimming Eotheroides sandersi green compared to three other Eocene sirenian taxa The teeth of Eotheroides were relatively unspecialized compared to those of extant sirenians which are reduced as an adaptation for feeding on sea grass The upper molars of E lambondrano are considerably longer and wider than those of E aegyptiacum suggesting that they were less specialized 1 Eotheroides is likely to have been one of the first fully aquatic sea cows Eotheroides lambondrano was found in association with the remains of other sea cows crocodilians and sea turtles which suggests that the locality is representative of a coastal or estuarine environment 3 References edit a b c Gingerich P D Domning D P Blane C E Uhen M D 1994 Late Eocene sea cows Mammalia Sirenia from Wadi Al Hitan in the Fayum Basin Egypt Contributions from the Museum of Paleontology 29 2 University of Michigan 41 67 Samonds K E Zalmout I S Irwin M T Krause D W Rogers R R Raharivony L L 2009 Eotheroides lambondrano new Middle Eocene seacow Mammalia Sirenia from the Mahajanga Basin Northwestern Madagascar Journal of Vertebrate Paleontology 29 4 1233 1243 Bibcode 2009JVPal 29 1233S doi 10 1671 039 029 0417 S2CID 59466434 a b Ancient Pygmy Sea Cow Discovered Science Daily 18 December 2009 Retrieved 18 December 2009 Bajpai S Thewissen J G M Kapur V V Tiwari B N Sahni A 2006 Eocene and Oligocene sirenians Mammalia from Kachchh India Journal of Vertebrate Paleontology 26 2 400 410 doi 10 1671 0272 4634 2006 26 400 eaosmf 2 0 co 2 S2CID 86682899 Zdansky O 1138 Eotherium majus sp n eine neue Sirene aus dem Mitteleozan von Agypten Palaeobiologica 6 429 434 a b Iyad S Zalmout and Philip D Gingerich 2012 Late Eocene Sea Cows Mammalia Sirenia From Wadi Al Hitan In The Western Desert of Fayum Egypt University of Michigan Papers on Paleontology 37 1 158 hdl 2027 42 94568 Das D P Basu P K 1994 Study of Palaeogene marine mammals of Kachchh Guarat Geological Survey of India 127 2 5 Gingerich P D 1992 Marine Mammals Cetacean and Sirenia from the Eocene of Gebel Mokattam and Fayum Egypt Stratigraphy Age and Paleoenvironments Contributions from the Museum of Paleontology 30 University of Michigan 1 84 Further reading editMarine Mammals Evolutionary Biology by Annalisa Berta James L Sumich and Kit M Kovacs The Beginning of the Age of Mammals by Kenneth D Rose Classification of Mammals by Malcolm C McKenna and Susan K BellExternal links editPrehistoric Pygmy Sea Cow Discovered in Madagascar Eotheroides in the Paleobiology Database Retrieved from https en wikipedia org w index php title Eotheroides amp oldid 1192671057, wikipedia, wiki, book, books, library,
