| Babiacetus | |
|---|---|
 | |
| lower jaw of Babiacetus | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Artiodactyla |
| Infraorder: | Cetacea |
| Family: | †Protocetidae |
| Subfamily: | †Georgiacetinae |
| Genus: | †Babiacetus Trivedy & Satsangi 1984 |
| Species | |
| |
Babiacetus is anextinctgenus of earlycetacean that lived during the lateLutetianmiddle Eocene ofIndia (47.8 to 40.4 million years ago).[1][2]It was named after its type locality, theHarudi Formation[3] in theBabia Hills (23°30′N68°48′E / 23.5°N 68.8°E /23.5; 68.8: paleocoordinates5°54′N61°48′E / 5.9°N 61.8°E /5.9; 61.8),Kutch District, Gujarat, India.[2]
Babiacetus was named byTrivedy & Satsangi 1984 in an abstract based on the specimen's type (GSI 19647, left and right dentaries with cheek teeth).[4] Gingerich and colleagues found a skull (GSP-UM 3005, much of a skull and lower jaws)[4] while collecting a skeleton of a new species ofProtosiren (Protosiren sattaensis)[5] in theDrazinda Formation (30°48′N70°30′E / 30.8°N 70.5°E /30.8; 70.5, paleocoordinates16°54′N67°06′E / 16.9°N 67.1°E /16.9; 67.1)[6] in theSulaiman Range ofPunjab, Pakistan.Gingerich et al. 1995 described both the original find and their new specimen.[7]Bajpai & Thewissen 1998 describedB. mishrai from the specimen (RUSB 2512, a partial skull)[4] collected in the Harudi Formation.[7][8]
Babiacetus is one of the larger protocetids weighing about 830 kilograms (1,830 lb).[9][10] Its hydrodynamic skull and pointed, anteroposteriorly (front-back) oriented incisors are typical of archaeocetes. A densely ossifiedauditory bulla and largemandibular canal indicate it was adapted for hearing in water.[11]Babiacetus differs from pakicetids and ambulocetids (more primitive families) by the large mandibular foramen and a medially concaveascending ramus; distinct from remingtonocetids and basilosaurids (more derived families) by the single-cuspedtrigonid andtalonid on the lower molars.[7] Its longsynostotic (fused)mandibular symphysis, which reaches as far back as P2, distinguishes it fromPappocetus andGeorgiacetus (other protocetids). Its auditory bulla is more narrow thanRodhocetus'.Babiacetus lacks the prominent molar protocone present inIndocetus.[12]The anterior premolars are large.[9]
Its large size as well as robust teeth suggest that it fed on larger fishes or aquatic vertebrates, or both. To date, only cranial remains have been found, hence nothing is known ofBabicetus' mode of locomotion or degree of aquatic adaptation.[11]
The mandible is longer inB. indicus than inB. mishrai, and P1 is single-rooted in the former but double-rooted in the latter. Thediastemata between P1 and P4 inB. indicus is absent inB. mishrai.B. indicus has larger cheek teeth and a larger M3.[12]
