Archaeoceti geological ages 01
Pakicetidae are primarily found in the lower Kuldana Formation,[1] but have also been found further up, with some species of Pakicetus overlapping the geological range of the remingtonocetid Attockicetus.[2]
- Pakicetus was previously dated to 52 million years,[3] but have subsequently been dated to 48 million years.[4]
- Ichthyolestes is contemporaneous to Pakicetus.[2]
- Nalacetus is contemporaneous to Pakicetus.[2]
Ambulocetidae is estimated to have lived about 52-49 million years ago.[5]
- Himalayacetus is dated to 53.5 million years.[4]
- Gandakasia stems from a layer below the remains of Ambulocetus.[2]
- Ambulocetus is dated to 48-47 million years.[6]
Remingtonocetidae is dated to 49-43 million years ago.[5]
- Dalanistes dates to 46.5-46 million years ago.[7]
- Remingtonocetus dates to 46.5-46 million years ago.[7]
- Kutchicetus dates to 46-43 million years ago.[5] fossil remains stem from Harudi Formation in India, considered to be from the Lutetian, about 46-42 million years (or possibly 43-41 million years).[8]
- Andrewsiphius fossil remains stem from Harudi Formation in India, considered to be from the Lutetian, about 6-42 million years (or possibly 43-41 million years).[8]
- Attockicetus fossil range in Kuldana Formation overlap with late Pakicetus and precede as well as exceed that of Ambulocetus.[2]
- Rayanistes[9]
Protocetidae consist of several genera spanning the Middle Eocene, roughly 49-37 million years ago.[10]Aegicetus expand the ending date to 35 million years ago.
- Maiacetus is the oldest protocetid, dated to 47.5 million years.[10]
- Artiocetus 47 million years.[6]
- Rodhocetus 47-46.5 million years.[11][6]
- Tacracetus 46.5-46 million years[7] (not included in the diagram).
- Gaviacetus 46.5-46 million years.[7]
- Protocetus 46-45 million years.[11]
- Qaisracetus have been given a date of 43 million years.[12]
- Peregocetus 42.6 million years.[13]
- Natchitochia are known from fossils dug up in Louisiana, USA. The holotype fossil (USNM 16805) was found in Milams members layers of Cook Mountain Formation[14] (dated to Early Bartonian).[15] The Milams members layers is believed to have been laid down 41.3-39.5 million years ago.[16] The specimen MMNS VP-48-49 was found in the lowest part of the Milams (Archusa Marl member).[17] This would give it a date of about 41 millon years.
- Aegypteocetus is dated to 41-40 million years[18]
- Georgiacetus has been given dates of 41-40 million years[19] or 41-38 million years.[5]
- Aegicetus is the protocetid with the most recent date of 35 million years.[20]
Basilosauridae have been dated to 40-34 million years,[10] with the Priabonian Cynthiacetus and Saghacetus as the most recent genera.[21] An isolated jawbone (MLP 11-II-21-3) found at Seymour Island (Antarctica) in 2011 could potentially push back the temporal rage of the family.[22]
- MLP 11-II-21-3 is a specimen consisting of a single jawbone found in Antarctica. It was first said to be 49 million years,[23] but it has been difficult to decide an age of the rocks in which it was found.[22] In 2019, it was given an age of 46-40 million years.[24]
- USNM 310633 (dated to 42 million years)[25] was originally described as a protocetid and named Eocetus wardii by Mark Uhen 1999.[26]It was re-classified in 2013 to a new genus of basilosaurid, Basilotritus,[27] and subsequently to Pachycetus[28]
- Tutcetus have been dated to the Early Bartonian (41 million years ago) and described as "one of the oldest [basilosaurid] records worldwide".[29]
- Basilosaurus fossils have been assigned to the Priabonian and Bartonian stages of Eocene, 40-37 million years ago.[6][30]
- Perucetus have been dated to 38 million years.[31]
- Dorudon are stated by some sources to be 37 million years old,[6] while others gives a date of 41-40 million years.[32]
References
- ↑ [1]
- ↑ a b c d e [2]
- ↑ [3]
- ↑ a b [4]
- ↑ a b c d Thewissen J.G.M. & Bajpai S, 2001, “Whale Origins as a Poster Child for Macroevolution”, BioScience 51(12): p. 1037-1049
- ↑ a b c d e [5]
- ↑ a b c d [6]
- ↑ a b [7]
- ↑ [8]
- ↑ a b c Gingerich P.G. et.al. (2009). "New Protocetid Whale from the Middle Eocene of Pakistan: Birth on Land, Precocial Development, and Sexual Dimorphism". PLoS ONE 4(2): e4366
- ↑ a b [9]
- ↑ [10]
- ↑ [11]
- ↑ Uhen M.D. (1998). "New protocetid (Mammalia, Cetacea) from the late middle Eocene Cook Mountain Formation of Louisiana", Journal of Vertebrate Paleontology 18(3): p. 664-668
- ↑ [12]
- ↑ [13], diagram at p. 7
- ↑ Uhen M.D. (2014). "New material of Natchitochia jonesi and a comparison of the innominata and locomotor capabilities of Protocetidae", Marine Mammal Science 30(3): p. 1029-1066
- ↑ [14]
- ↑ [15]
- ↑ [16]
- ↑ [17]
- ↑ a b [18]
- ↑ [19]
- ↑ [20]
- ↑ Geisler J.H., Sanders A.E. & Lou Z-X. (2005). "A New Protocetid Whale (Cetacea: Archaeoceti) from the Late Middle Eocene of South Carolina", American Museum Novitates no. 3480: p. 1-65
- ↑ Uhen M. (1999). "New Species of Protocetid Archaeocete Whale, Eocetus wardii (Mammalia: Cetacea) from the Middle Eocene of North Carolina". Journal of Paleontology 73(3): p. 512-528
- ↑ Gol'din P & Zvonok E.A. (2013). "Basilotritus uheni, a New Cetacean (Cetacea, Basilosauridae) from the Late Middle Eocene of Eastern Europe". Journal of Paleontology 87(2): p. 254-268
- ↑ van Vliet H.J., Bosselaers M, Vahldiek B-W., Paymans T & Verheijen I (2020). "Eocene cetaceans from the Helmstedt region, Germany, with some remarks on Platyosphys, Basilotritus and Pachycetus", Cainozoic Research 20(1): p. 121-148
- ↑ Antar M.S. et.al. (2023). "A diminutive new basilosaurid whale reveals the trajectory of the cetacean life histories during the Eocene". Communications Biology 6:article 707
- ↑ The Paleobiology Database: "Basilosaurus" (read 29-11-2020)
- ↑ Bianucci G et.al.. "A heavyweight early whale pushes the boundaries of vertebrate morphology". Nature (published online 2/8/2023)
- ↑ Uhen M.D. (2004). "Form, Function, and Anatomy of Dorudon Atrox (Mammalia, Cetacea): An Archaeocete from the Middle to Late Eocene of Egypt". The University of Michigan Museum of Paleontology Papers on Paleontology 34: 222 pages
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