''Andrewsiphius'' is an extinct remingtonocetid early whale known from the

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

(

Lutetian The Lutetian is, in the geologic timescale, a stage (stratigraphy), stage or age (geology), 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 ...

, ) of

Gujarat Gujarat () is a States of India, state along the Western India, western coast of India. Its coastline of about is the longest in the country, most of which lies on the Kathiawar peninsula. Gujarat is the List of states and union territories ...

and Kutch,

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

and

Balochistan Balochistan ( ; , ), also spelled as Baluchistan or Baluchestan, is a historical region in West and South Asia, located in the Iranian plateau's far southeast and bordering the Indian Plate and the Arabian Sea coastline. This arid region o ...

Pakistan Pakistan, officially the Islamic Republic of Pakistan, is a country in South Asia. It is the List of countries and dependencies by population, fifth-most populous country, with a population of over 241.5 million, having the Islam by country# ...

Discovery and naming

The first specimen was collected by who described it as

mandibular In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...

fragments of ''

Protocetus ''Protocetus atavus'' ("first whale") is an extinct species of primitive cetacean from Egypt. It lived during the middle Eocene period 45 million years ago. The first discovered protocetid, ''Protocetus atavus'' was described by based on a cran ...

sloani''. described two new species, ''Andrewsiphius kutchensis'' and ''A. minor'' based on their previous material and new mandibular fragments. Later researchers interpreted the same mandibular specimens as belonging to ''Remintonocetus''. reinterpreted these specimens as fragments from

maxilla In vertebrates, the maxilla (: maxillae ) is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxil ...

e, and determined that the described "confluence of the

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 ...

s anteriorly" was in fact the narial passages. Gingerich et al. also determined that the variations in size among proposed species were within the normal variation for a single species and therefore attributed a number of referred specimens as belonging to ''Andrewsiphius sloani''. Gingerich et al. also noted that the type specimen of '' Kutchicetus minimus'' came from the same locality as ''A. sloani'' and that its distinctive small size was within the variation that could be expected for ''A. sloani'', and Gingerich et al. therefore included ''K. minimus'' into ''A. sloani''. Later authors, however, disagreed on this assignment and ''Kutchicetus'' is still accepted as a separate genus. named the type species for Dr Robert E. Sloan, Department of Geology, University of Minnesota.

Description

''Andrewsiphius'' is similar to but smaller than '' Kutchicetus'' (another remingtonocetid); synonymized them, and proposed a new subfamily, Andrewsiphiinae, for the two species. Later authors, however, still accept both as separate genera. ''Andrewsiphius'' and ''Kutchicetus'' share several characteristics not present in other remingtonocetids: an elongated snout that is higher than it is wide;

foramina In anatomy and osteology, a foramen (; : foramina, or foramens ; ) is an opening or enclosed gap within the dense connective tissue (bones and deep fasciae) of extant and extinct amniote animals, typically to allow passage of nerves, arter ...

(small holes) on the tip of the snout suggesting the presence of whiskers; eyes located dorsally near the cranial midline, resulting in an appearance of a mammalian crocodile; and a very large

sagittal crest A sagittal crest is a ridge of bone running lengthwise along the midline of the top of the skull (at the sagittal suture) of many mammalian and reptilian skulls, among others. The presence of this ridge of bone indicates that there are excepti ...

overhanging the back of the skull. Other characteristics make them distinct: the second and third upper and lower premolars are double-rooted in ''Andrewsiphius'' but single-rooted in ''Kutchicetus''; the large diastemata in the former are absent the latter; and the tail vertebrae are more robust in ''Andrewsiphius''. ''Andrewsiphius'' is, compared to the remgintonocetids ''

Remingtonocetus ''Remingtonocetus'' is an extinct genus of early cetacean freshwater aquatic mammals of the family (biology), family Remingtonocetidae endemic to the coastline of the ancient Tethys Ocean during the Eocene. It was named after naturalist Remington ...

'' and '' Dalanistes'', smaller, has a narrower

rostrum Rostrum may refer to: * Any kind of a platform for a speaker: **dais **pulpit ** podium * Rostrum (anatomy), a beak, or anatomical structure resembling a beak, as in the mouthparts of many sucking insects * Rostrum (ship), a form of bow on naval ...

, and smaller premolars separated by longer diastemata.

Notes

References

* * * * * {{Taxonbar, from=Q5675355 Remingtonocetidae Fossil taxa described in 1975 Monotypic prehistoric cetacean genera Eocene mammals of Asia