Indocetus

Indocetus
Temporal range: late early Eocene (Lutetian), 48.6–40.4 Ma
Lower jaw of Indocetus
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Infraorder: Cetacea
Family: †Protocetidae
Subfamily: †Protocetinae
Genus: †Indocetus
Sahni & Mishra, 1975
Species[1]
  • I. ramani
    Sahni & Mishra, 1975

Indocetus is a protocetid early whale known from the late early Eocene (Lutetian, 48.6 to 40.4 million years ago) Harudi Formation (23°30′N 68°42′E / 23.5°N 68.7°E / 23.5; 68.7, paleocoordinates 5°54′N 61°42′E / 5.9°N 61.7°E / 5.9; 61.7)[2] in Kutch, India.

The holotype of Sahni & Mishra 1975 is a partial skull in two pieces with the frontal shield and the right occiput and auditory bulla preserved.[3]

Gingerich et al. 1993 described postcranial remains from the Sulaiman Range, Punjab, Pakistan, and attributed them to Indocetus. Gingerich, Arif & Clyde 1995, however, withdrew this assignment and instead attributed this postcranial material to Remingtonocetus because of similarities to the then newly discovered remingtonocetid Dalanistes, including a longer neck and fused sacral vertebral elements.[4] This leaves Indocetus without postcranial remains, but undescribed material (as of 1998) from Kutch most likely include some that can be attributed to Indocetus. Furthermore, Rodhocetus, also from Sulaiman, is very similar to Indocetus and it is possible that these genera are synonyms.[5]

Indocetus is known from a partial skull, two endocasts, a right tympanic, and a right maxilla; all from the Harudi Formation. Indocetus has prominent protocones on the molars, distinguishing it from Protocetus, Eocetus, Babiacetus, and Georgiacetus. P1 is single-rooted like Rodhocetus. The tympanic bulla is more narrow than in Protocetus and Georgiacetus.[6]

The endocasts included dental material, including alveoli and the bases of cheek teeth but not the crowns. P3–4 are three-rooted and probably had protocones. The molars are smaller than the premolars and decrease from M1 to M3. M1 and M2 have large protocone lobs.[5]

Notes

  1. ^ Indocetus in the Paleobiology Database. Retrieved 27 July 2013.
  2. ^ Harudi (Eocene of India) in the Paleobiology Database. Retrieved 27 July 2013.
  3. ^ Gingerich et al. 1993, pp. 396, 410
  4. ^ Gingerich, Arif & Clyde 1995, p. 328
  5. ^ a b Bajpai & Thewissen 1998, pp. 223–5
  6. ^ Williams 1998, p. 12

References

  • Bajpai, S.; Thewissen, J. G. M. (1998). "Middle Eocene Cetaceans from the Harudi and Subathu Formations of India". In Thewissen, J. G. M. (ed.). The Emergence of Whales: Evolutionary Patterns in the Origin of Cetacea. Advances in vertebrate paleobiology. New York: Plenum Press. pp. 213–233. ISBN 9780306458538. OCLC 300450327. Retrieved 27 July 2013.
  • Gingerich, P. D.; Raza, S. Mahmood; Arif, Muhammad; Anwar, Muhammad; Zhou, Xiaoyuan (1993). "Partial skeletons of Indocetus ramani (Mammalia, Cetacea) from the lower middle Eocene Domanda Shale in the Sulaiman Range of Punjab (Pakistan)" (PDF). Contributions from the Museum of Paleontology, the University of Michigan. 28 (16): 393–416. Retrieved 27 July 2013.
  • Gingerich, P. D.; Arif, Muhammad; Clyde, William C. (1995). "New Archaeocetes (Mammalia, Cetacea) from the middle Eocene Domanda Formation of the Sulaiman Range, Punjab (Pakistan)". Contributions from Museum of Paleontology, the University of Michigan. 29 (11): 291–330. hdl:2027.42/48650. OCLC 34123868.
  • Sahni, Ashok; Mishra, Vijay Prakash (1975). "Lower Tertiary vertebrates from western India". Monograph of the Paleontological Society of India. 3: 1–48. ASIN B0007AL8UE. OCLC 3566369.
  • Williams, Ellen (1998). "Synopsis of the Earliest Cetaceans: Pakicetidae, Ambulocetidae, Remingtonocetidae, and Protocetidae". In Thewissen, J.G.M. (ed.). The Emergence of Whales: Evolutionary Patterns in the Origin of Cetacea. Advances in Vertebrate Paleobiology. Springer. pp. 2–15. ISBN 9780306458538. OCLC 300450327.