''Babiacetus'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of early

cetacea Cetacea (; , ) is an infraorder of aquatic mammals that includes whales, dolphins, and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel them ...

n that lived during the late

Lutetian The Lutetian is, in the geologic timescale, a stage or age in the Eocene. It spans the time between . The Lutetian is preceded by the Ypresian and is followed by the Bartonian. Together with the Bartonian it is sometimes referred to as the Midd ...

middle Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', "dawn ...

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

().. Retrieved April 2013. It was named after its type locality, the Harudi Formation in the Babia Hills (: paleocoordinates ), Kutch District, Gujarat, India. ''Babiacetus'' was named by in an abstract based on the specimen's type (GSI 19647, left and right dentaries with cheek teeth). Gingerich and colleagues found a skull (GSP-UM 3005, much of a skull and lower jaws) while collecting a skeleton of a new species of

Protosiren ''Protosiren'' is an extinct early genus of the order Sirenia. ''Protosiren'' existed throughout the Lutetian to Priabonian stages of the Middle Eocene. Fossils have been found in the far-flung locations like the United States (South Carolina, No ...

(''Protosiren sattaensis'') in the Drazinda Formation (, paleocoordinates ) in the

Sulaiman Range The Sulaiman Mountains, also known as Kōh-e Sulaymān ( Balochi/Urdu/ fa, ; "Mountains of Solomon") or Da Kasē Ghrūna ( ps, د كسې غرونه; "Mountains of Kasi"), are a north–south extension of the southern Hindu Kush mountain system i ...

Punjab Punjab (; Punjabi: پنجاب ; ਪੰਜਾਬ ; ; also romanised as ''Panjāb'' or ''Panj-Āb'') is a geopolitical, cultural, and historical region in South Asia, specifically in the northern part of the Indian subcontinent, comprising ...

, Pakistan. described both the original find and their new specimen. described '' B. mishrai'' from the specimen (RUSB 2512, a partial skull) collected in the Harudi Formation.. Retrieved March 2013. ''Babiacetus'' is one of the larger protocetids. Its hydrodynamic skull and pointed, anteroposteriorly (front-back) oriented incisors are typical of archaeocetes. A densely ossified

auditory bulla The tympanic part of the temporal bone is a curved plate of bone lying below the squamous part of the temporal bone, in front of the mastoid process, and surrounding the external part of the ear canal. It originates as a separate bone (tympanic ...

and large

mandibular canal In human anatomy, the mandibular canal is a canal within the mandible that contains the inferior alveolar nerve, inferior alveolar artery, and inferior alveolar vein. It runs obliquely downward and forward in the ramus, and then horizontally f ...

indicate it was adapted for hearing in water. ''Babiacetus'' differs from pakicetids and ambulocetids (more primitive families) by the large mandibular foramen and a medially concave ascending ramus; distinct from remingtonocetids and basilosauroids (more derived families) by the single-cusped

trigonid The molars or molar teeth are large, flat tooth, teeth at the back of the mouth. They are more developed in mammal, mammals. They are used primarily to comminution, grind food during mastication, chewing. The name ''molar'' derives from Latin, ...

and

talonid The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone to ...

on the lower molars. Its long synostotic (fused)

mandibular symphysis In human anatomy, the facial skeleton of the skull the external surface of the mandible is marked in the median line by a faint ridge, indicating the mandibular symphysis (Latin: ''symphysis menti'') or line of junction where the two lateral halves ...

, which reaches as far back as P₂, distinguishes it from ''

Pappocetus } ''Pappocetus'' is an extinct protocetid cetacean known from the Eocene of Nigeria and Togo. The type specimen BMNH M11414 an incomplete left mandible with symphysis, a deciduous premolar, and unerupted molars. It was found in Bartonian () la ...

'' and ''

Georgiacetus ''Georgiacetus'' is an extinct genus of ancient whale known from the Eocene period of the United States. Fossils are known from Georgia, Alabama, and Mississippi and protocetid fossils from the right time frame, but not yet confirmed as ''Georg ...

'' (other protocetids). Its auditory bulla is more narrow than ''

Rodhocetus ''Rodhocetus'' (from ''Rodho'', the geological anticline at the type locality, and ''cetus'', Latin for whale) is an extinct genus of protocetid early whale known from the Lutetian of Pakistan. The best-known protocetid, ''Rodhocetus'' is known ...

'''. ''Babiacetus'' lacks the prominent molar protocone present in ''

Indocetus ''Indocetus'' is a protocetid early whale known from the late early Eocene (Lutetian, ) Harudi Formation (, paleocoordinates ) in Kutch, India. The holotype of is a partial skull in two pieces with the frontal shield and the right occiput a ...

''. The anterior premolars are large. 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 of ''Babicetus''' mode of locomotion or degree of aquatic adaptation. The mandible is longer in '' B. indicus'' than in ''B. mishrai'', and P₁ is single-rooted in the former but double-rooted in the latter. The diastemata between P₁ and P₄ in ''B. indicus'' is absent in ''B. mishrai''. ''B. indicus'' has larger cheek teeth and a larger M₃.

Notes

References

* * * * {{Taxonbar, from=Q16748752 Protocetidae Prehistoric cetacean genera Fossil taxa described in 1984 Extinct animals of India