Eocetus
Eocetus | |
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Scientific classification ![]() | |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Artiodactyla |
Infraorder: | Cetacea |
Family: | †Protocetidae |
Subfamily: | †Georgiacetinae |
Genus: | †Eocetus Fraas, 1904 |
Type species | |
†Eocetus schweinfurthi | |
Other species | |
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Synonyms | |
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Eocetus is an extinct protocetid early whale known from the early late Eocene (Bartonian, 40.4 to 37.2 million years ago) in Gebel Mokattam, (30°00′N 31°18′E / 30.0°N 31.3°E, paleocoordinates 24°54′N 26°48′E / 24.9°N 26.8°E) outside Cairo, Egypt.[1][2] The specimen was first named by Fraas as Mesocetus schweinfurthi. However, the name Mesocetus was previously used causing a change to the species name to Eocetus schweinfurthi. Since the genus was first described in the early 20th century, several other specimens, mostly isolated vertebrae, have been attributed to Eocetus, but the taxonomic status of these widely distributed specimens remain disputed.
Discovery and taxonomy[]
Fraas 1904a described "Mesocetus schweinfurthi" based on a dorsoventrally compressed skull with only I2 in situ, a specimen supposedly originating from a 40 Ma Tethyan deposit at Mokattam. Fraas also referred two isolated teeth, P4 and M1, to the skull and the most important of his specimens is not the deformed skull, but the upper molar which retains three roots and a worn but well-developed protocone. Georg August Schweinfurth, a German palaeontologist who explored Mokattam in the 1880s, mentioned the quarriers there very eagerly offered "shark teeth" to tourists and that scientists and fossil collectors regularly bought their specimens from this source. There is reason to assume that Fraas were among them and that at least his two isolated teeth were described without direct knowledge of their original locality and stratigraphic context. Notwithstanding that the stratigraphic information supplied by Fraas and his contemporaries can be difficult to interpret, the geology of Egypt is well-studied, and both the skull and the accompanying teeth are most likely Bartonian in age – older and significantly more primitive than any other cetacean specimen known from Egypt at that time.[3][4] Fraas soon discovered that the name "Mesocetus" was already occupied, and changed the name of his "Urform Protocetus" to Eocetus.[5]
Fraas also attributed two isolated vertebrae to his new genus, both of which Uhen 1998 moved to Basilosaurus drazindai. A holotype, described by Stromer 1903 as Zeuglodon macrospondylus, was discovered in Egypt. It is later used for comparison for other vertebrae. Stromer 1908 attributed two other vertebrae from Mokattam to Eocetus. These two vertebrae were lost for many years until Uhen 1999 described two bones that he discovered in a museum in Germany and appeared to fit Stromer's description. Uhen based his assignment of his own North American genus (see below) to Eocetus on the similarities to Stromer's vertebrae.[6]
Previously-assigned specimens and taxa[]
Uhen 1999 described a new species, Eocetus wardii, from the late Lutetian (~42 Ma) of North Carolina based on more complete material: a partial skull, a few thoracic, lumbar and caudal vertebrae, ribs and an innominate fragment. Uhen initially argued that the innominate would have been sufficiently large to support a weight-bearing hind limb – suggesting the animal was a protocetid, a group of more primitive archaeocetes – but also has anatomical features in common with basilosaurids – more derived and fully aquatic archaeocetes. Uhen also noted that the composition of the ribs and vertebrae is different from that of other archaeocetes and sirenians: a core of light trabecular bone is surrounded by layers of dense cortical bone.[7] Due to this mosaic of protocetid and basilosaurid features, Geisler, Sanders & Luo 2005 regarded Uhen's specimen as unique among North American archaeocetes and an interesting find, but questioned the validity of Uhen's attribution (including that of Stromer's two vertebrae). This suspicion was confirmed by Goldin & Zvonok 2013 , who reassigned E. wardii remains to the genus Basilotritus (and hence Basilosauridae),[8] while Gol’din have concluded that the original interpretation of its innominate were incorrect, and that the hips could have been more reduced and Basilosaurus-like than Uhen first thought.[9]
Uhen & Berndt 2008 described another partial lumbar vertebra discovered in Rohrdorf, Bavaria, Germany, in 2003. They attributed it to Eocetus sp. – the first confirmed protocetid from Europe – and argued that this specimen further supports the hypothesis that protocetids were aquatic to the extent that they managed to spread over the world.[10][11]
Two vertebrae, a thoracic and a lumbar, discovered on a riverbed in Virginia in 2009 were referred to "Eocetus" wardi by Weems et al. 2011.[12][13]
Uhen et al. 2011 described a still unnamed Bartonian protocetid from Peru based on the posterior portion of a skull, seven partial vertebrae, and ribs from and adult individual. Uhen et al. considered this specimen closely related to Eocetus based on vertebral morphology.[14]
Goldin, Zvonok & Krakhmalnaya 2012 described two vertebra, a thoracic and a lumbar, from a subadult individual found in Ukraine. They considered them comparable to those Uhen described in 1999 and attributed their specimen to "E." wardii.[15]
References[]
Notes[]
- ^ Eocetus in the Paleobiology Database. Retrieved 1 July 2013.
- ^ Gebel Mokattam, upper (Eocene of Egypt) in the Paleobiology Database. Retrieved 1 July 2013.
- ^ Bianucci & Gingerich 2011, p. 1174
- ^ Gingerich 1992, pp. 71–2
- ^ Fraas 1904b, p. 374
- ^ Geisler, Sanders & Luo 2005, p. 47
- ^ Uhen 1999, Abstract
- ^ Goldin & Zvonok 2013, Abstract
- ^ Gol’din, P.(2014). "Naming an Innominate: Pelvis and Hindlimbs of Miocene Whales Give an Insight into Evolution and Homology of Cetacean Pelvic Girdle”. Evolutionary Biology 41: p. 473—479. DOI:10.1007/s11692-014-9281-8
- ^ "Eocetus sp". Collections Search Center, Smithsonian Institution. Retrieved 1 July 2013.
- ^ Uhen & Berndt 2008, Abstract
- ^ Weems et al. 2011, Abstract
- ^ Weems et al. 2011, Material, p. 273
- ^ Uhen et al. 2011
- ^ Goldin, Zvonok & Krakhmalnaya 2012, Introduction
Sources[]
- Bianucci, Giovanni; Gingerich, Philip D. (2011). "Aegyptocetus tarfa, n. gen. et sp. (Mammalia, Cetacea), from the middle Eocene of Egypt: clinorhynchy, olfaction, and hearing in a protocetid whale". Journal of Vertebrate Paleontology. 31 (6): 1173–88. doi:10.1080/02724634.2011.607985. S2CID 85995809.
- Fraas, Eberhard (1904a). "Neue Zeuglodonten aus dem unteren Mitteleocän vom Mokattam bei Cairo". Geologische und Paläontologische Abhandlungen. Jena: Verlag Gustav Fischer. 6 (3): 199–220. OCLC 17663675. Retrieved 1 July 2013.
- Fraas, E. (1904b). "Neue Zeuglodonten aus dem unteren Mitteleocän vom Mokattam bei Cairo". Geologische Zentralblatt. Leipzig. 5: 374. Retrieved 1 July 2013.
- Geisler, Jonathan H; Sanders, Albert E; Luo, Zhe-Xi (2005). "A new protocetid whale (Cetacea, Archaeoceti) from the late middle Eocene of South Carolina". American Museum Novitates. 3480: 1–68. doi:10.1206/0003-0082(2005)480[0001:ANPWCA]2.0.CO;2. OCLC 4630500767.
- Gingerich, P. D. (1992). "Marine Mammals (Cetacea and Sirenia) from the Eocene of Gebel Mokattam and Fayum, Egypt: Stratigraphy, Age and Paleoenvironments". Papers on Paleontology. Museum of Paleontology, The University of Michigan. hdl:2027.42/48630. OCLC 742731517.
- Gingerich, P.D.; Arif, M.; Bhatti, M.A.; Anwar, M.; Sanders, W.J. (1997). "Basilosaurus drazindai and Basiloterus hussaini, New Archaeoceti (Mammalia, Cetacea) from the Middle Eocene Drazinda Formation, with a Revised Interpretation of Ages of Whale-bearing Strata in the Kirthar Group of the Sulaiman Range, Punjab (Pakistan)". Contributions from the Museum of Paleontology, University of Michigan. 30: 55–81. hdl:2027.42/48652.
- Gol'din, Pavel & Zvonok, Evgenij (2013). "Basilotritus uheni, a New Cetacean (Cetacea, Basilosauridae) from the Late Middle Eocene of Eastern Europe". Journal of Paleontology. 87 (2): 254–268. doi:10.1666/12-080R.1. S2CID 83864139.
- Goldin, P.; Zvonok, E.; Krakhmalnaya, T. (2012). "New records of "Eocetus" sp. (Mammalia: Сetacea) from the Eocene of Ukraine". Ukrainian Geologist Journal. 3 (39): 104–. Retrieved 1 July 2013. (PDF[permanent dead link])
- Stromer, Ernst (1908). Die Archaeoceti des ägyptischen Eozäns: Beiträge zur paläontologie und geologie Österreich-Ungarns und des Orients (PDF). W. Braumüller. OCLC 21174007. Retrieved 1 July 2013.
- Uhen, Mark D. (1998). "Middle to late Eocene basilosaurines and dorudontines". In Thewissen, J. G. M. (ed.). The emergence of whales, evolutionary patterns in the origin of Cetacea. New York: Plenum Press. pp. 29–61. ISBN 9780306458538.
- Uhen, Mark D. (1999). "New species of protocetid archaeocete whale, Eocetus wardii (Mammalia, Cetacea) from the middle Eocene of North Carolina". Journal of Paleontology. 73 (3): 512–528. doi:10.1017/S002233600002802X. Retrieved 1 July 2013.
- Uhen, Mark D.; Berndt, Hans-Jürgen (2008). "First record of the aracheocete whale family Protocetidae from Europe". Fossil Record. 11 (2): 57–60. doi:10.1002/mmng.200800001.
- Uhen, Mark D.; Pyenson, Nicholas D.; Devries, Thomas J.; Urbina, Mario; Renne, Paul R. (2011). "New Middle Eocene Whales from the Pisco Basin of Peru". Journal of Paleontology. 85 (5): 955–69. doi:10.1666/10-162.1. hdl:10088/17509. OCLC 802202947. S2CID 115130412.
- Weems, Robert E.; Edwards, Lucy E.; Osborne, Jason E.; Alford, Aaron A. (2011). "An Occurrence of the Protocetid Whale "Eocetus" wardii in the Middle Eocene Piney Point Formation of Virginia". Journal of Paleontology. 85 (2): 271–278. doi:10.1666/10-083.1. S2CID 129160656. Retrieved 1 July 2013.
- Eocene mammals of Africa
- Protocetidae
- Fossil taxa described in 1904
- Prehistoric cetacean genera