''Dalanistes'' is an extinct genus of remingtonocetid early whale known from the late early

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

(

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 ...

, ) of Kutch, India and

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 ...

and

Balochistan Balochistan ( ; bal, بلۏچستان; also romanised as Baluchistan and Baluchestan) is a historical region in Western and South Asia, located in the Iranian plateau's far southeast and bordering the Indian Plate and the Arabian Sea coastline. ...

, Pakistan. ''Dalanistes'' is closely related to ''

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

'' (the type genus of Remingtonocetidae, a slightly more derived family of early whales), but also shares several features with ''

Ambulocetus ''Ambulocetus'' (Latin ''ambulare'' "to walk" + ''cetus'' "whale") is a genus of early amphibious cetacean from the Kuldana Formation in Pakistan, roughly 48 or 47 million years ago during the Early Eocene (Lutetian). It contains one species, ' ...

'' (the type of Ambulocetidae, earlier more primitive whales), and, with its combination of terrestrial and amphibious adaptations, ''Dalanistes'' apparently is an intermediate form between these two groups. Isotopic evidence suggest that ''Dalanistes'' had a marine diet. ''Dalanistes'' is known from several localities and collections. The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

is a skull and a postcranial skeleton. Additional fossils referred to ''Dalanistes'' include crania, several vertebrae and sacra, possible caudals, one side of the pelvis, and a distal femur. The

alveoli Alveolus (; pl. alveoli, adj. alveolar) is a general anatomical term for a concave cavity or pit. Uses in anatomy and zoology * Pulmonary alveolus, an air sac in the lungs ** Alveolar cell or pneumocyte ** Alveolar duct ** Alveolar macrophage * ...

is all that is left of the dentition, but the dental formula apparently was . The vertebral elements of the sacrum are solidly fused and form a well-developed articular surface for the pelvis. The ilium is robust and long, and has a large acetabulum similar to that in ''Remingtonocetus''. The femur had a spherical head, a medial condyle considerably larger than the lateral, and a shallow patellar groove. Taken together this morphology suggests the presence of well-developed hind limbs. ''Dalanistes'' was a small whale weighing . It was similar to but 20% larger than ''

''; the external nares are located more anteriorly (above C¹); the

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 exceptiona ...

is much higher; the rostrum is angled down 20° relative to the main axis of the braincase; the mandibular symphysis is relatively open (ends at P₃) and the mandibular canals fail to unite at the symphysis. This mandibular morphology is also different from that of ''

Andrewsiphius ''Andrewsiphius'' is an extinct Remingtonocetidae, remingtonocetid Archaeoceti, early whale known from the Eocene (Lutetian, ) of Gujarat and Kutch, India and Balochistan, Pakistan. Discovery and naming The first specimen was collected by who ...

'' (another remingtonocetid). ''Dalanistes'' was named by contracting "Dalana" and "-istes" to allude to the Greek name '' platanistes'' used for (unrelated)

South Asian river dolphin South Asian river dolphins are toothed whales in the genus ''Platanista'', which inhabit fresh water habitats in the northern Indian subcontinent. They were historically considered to be one species (''P. gangetica'') with the Ganges river dolp ...

. Both the genus and species name refer to local place names near the type locality: Dalana Nala and Basti Ahmed respectively.

Notes

References

* * {{Taxonbar, from=Q1064332 Remingtonocetidae Eocene mammals of Asia Extinct animals of Pakistan Fossil taxa described in 1995 Prehistoric cetacean genera

See also

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References