{{Short description|Extinct protocetid early whale}} {{Use dmy dates|date=March 2021}} {{Speciesbox | name = ''Ancalecetus'' | image = Ancalecetus simonsi.png | image_caption = Life restoration | fossil_range = {{Temporal range|37.2|33.9}} | genus = Ancalecetus | parent_authority = {{Harvnb|Gingerich|Uhen|1996}} | species = simonsi | authority = {{Harvnb|Gingerich|Uhen|1996}} }}
'''''Ancalecetus''''' (from Greek ''ankale'', "bent arm", and ''ketos'', "whale")<ref name="etym">{{Harvnb|Gingerich|Uhen|1996|loc=Etymology, p. 364}}</ref> is an extinct genus of early whale known from the Late Eocene (Priabonian, {{Mya|37.2|33.9}}) Birket Qarun Formation ({{Coord|29.3|30.0|display=inline}}, paleocoordinates {{Coord|24.6|26.2|display=inline}}) in Wadi Al-Hitan, Egypt.<ref>{{Paleodb|53294|Ancalecetus}}. Retrieved July 2013.</ref><ref>{{Paleodb|collection|28977|Wadi Hitan ZV-81 (Eocene of Egypt)}}. Retrieved July 2013.</ref> The species is named after anthropologist and primate researcher Elwyn L. Simons who discovered the type specimen in 1985.<ref name="etym"/>
The holotype is a partial cranium (the top of the skull was destroyed by erosion), both dentaries, 20 vertebrae and some sternal elements, partial ribs, and most of both forelimbs. ''Ancalecetus'' differs from other archaeocetes and modern whales in having narrow scapulae, very limited mobility in the shoulder joint, and fusion of the humerus, ulna, and radius at the elbow joint. In the wrist, the carpal bones are small like in ''Zygorhiza'', but, unlike in this other basilosaurid, the magnum is fused with the trapezoid in ''Ancalecetus''.<ref>{{Harvnb|Gingerich|Uhen|1996|pp=363–4}}</ref>
==Forelimbs== The well-preserved forelimbs are the most distinctive parts of ''A. simonsi''. A broad scapula and a ball-and-socket shoulder joint is characteristic of cetaceans, but ''Ancalecetus'' lacks both.
The interior surface of the narrow scapula is not broadly curved as in most cetaceans, but tightly curved. The roughened vertebral border suggests the presence of a cartilaginous extension that extends the surface of the scapula like in modern cetaceans. Compared to other cetaceans, the infraspinous fossa is smaller, the caudal border is less curved and not oriented posteriorly. The glenoid cavity is very shallow and directed posteriorly, rather than ventrally like in other cetaceans. Likewise, the oddly folded acromion is pointing ventrally and posteriorly, and not anteriorly as in other cetaceans.<ref name="limb">{{Harvnb|Gingerich|Uhen|1996|pp=388–93}}</ref>
Unlike in other basilosaurids, the humerus of ''Ancalecetus'' is flattened and has a relatively small head. The distal end has flat, textured surfaces for the articulation of the radius and ulna; these bones are fused on the left limb and tightly fitting and the right side, and neither permitted motion at the elbow joint.<ref name="limb"/>
==Dentition== Most of the upper dentition has been eroded away, but the dental formula of ''Ancalecetus'' most likely was {{DentalFormula|lower=3.1.4.2|upper=3.1.4.3}}. Tooth wear show that ''Ancalecetus'', like other basilosaurids, fed on larger prey, probably fish, that required mastication before swallowing and that the type specimen survived into adulthood.<ref name="dent">{{Harvnb|Gingerich|Uhen|1996|pp=373–7}}</ref>
The unfused mandibular symphysis reaches as far posteriorly as P<sub>2</sub>. The large mandibular foramina, which contain the auditory fat pad in modern whales, is very well preserved in ''Ancalecetus''.<ref name="dent"/>
==Notes== {{Portal|Cetaceans|Paleontology}} {{Reflist}}
==References== {{Wikispecies|Ancalecetus}} {{Refbegin}} * {{Cite journal |last1=Gingerich |first1=Philip D. |author-link=Philip D. Gingerich |last2=Uhen |first2=Mark D. |title=''Ancalecetus simonsi'', a new dorudontine archaeocete (Mammalia, Cetacea) from the early late Eocene of Wadi Hitan, Egypt |name-list-style=and |year=1996 |journal=Contributions from the Museum of Paleontology, University of Michigan |volume=29 |issue=13 |pages=359–401 |url=https://deepblue.lib.umich.edu/bitstream/handle/2027.42/48634/ID500.pdf |access-date=12 July 2024 |oclc=742731018}}<!-- {{Harvnb|Gingerich|Uhen|1996}} --> {{Refend}}
{{Archaeoceti}} {{Taxonbar|from=Q1062904}} {{Authority control}}
Category:Basilosauridae Category:Monotypic prehistoric cetacean genera Category:Fossil taxa described in 1996 Category:Eocene mammals of Africa