Editing Pakicetidae (section)

==Locomotion==
[[File:Pakicetus attocki.jpg|thumb|''Pakicetus attocki'']]
Interpretations of pakicetid habitat and [[Locomotion in animals|locomotory]] behaviour varies considerably. In 2001, it was concluded by Thiwissen et al. that "pakicetids were terrestrial mammals, no more amphibious than a [[tapir]]." According to them, none of the [[aquatic adaptation]]s found in the oldest obligate aquatic cetaceans, [[Basilosauridae|basilosaurids]] and [[Dorudontidae|dorudontids]], are present in pakicetids. Pakicetid cervical vertebrae are longer than in late Eocene whales, the thoracic vertebrae increase in size from the neck backwards, and the lumbar and caudal vertebrae are longer than in modern cetaceans (but still shorter than in some extinct cetaceans with undulating spines.) Motion in the spine of pakicetids was further reduced by the [[Revolute joint|revolute]] [[zygapophyses]] (processes between the vertebrae) like in stiff-backed runners such as [[Mesonychia|mesonychians]]. The sacral vertebrae are fused and the sacroiliac joints present like in land mammals and amphibious cetaceans.<ref name="Thewetal-2001">{{Harvnb|Thewissen|Williams|Roe|Hussain|2001| pp=277–8}}</ref>

Furthermore, according to [[Hans Thewissen|Thewissen]] et al. (2001), the pakicetid [[Scapula|scapulae]] have large [[Supraspinous fossa|supraspinous fossae]] with small acromions, in contrast to other cetaceans. The [[deltopectoral crest]]s are absent in the long and slender humeri like in cursorial animals but unlike other Eocene cetaceans.  Pakicetid elbows are rigid hinge joints like in running mammals and the forearms are not flattened like in truly aquatic cetaceans. In the pakicetid pelvis, the innominates are large and the ischia are longer than the ilia.  The pakicetid tibiae are long with a short tibial crest. Hindlimb features that all more reminiscent of running and jumping animals than swimming animals.<ref name="Thewetal-2001" />

{{Harvnb|Gingerich|2003}} [[disagreed]] and got support from {{Harvnb|Madar|2007}}: [[postcrania]]l morphology and microstructural features suggest that pakicetids were adapted to an aquatic lifestyle which included bottom wading, paddling, and undulatory swimming, but probably not sustained running.  Isotopic evidence indicate Pakicetids spent a considerable part of their life in freshwater and probably ate freshwater prey.<ref name="Uhen-2010" /> This view was further reiterated by Gingerich in a 2017 paper.<ref>{{Cite journal |last=Gingerich |first=Philip D. |last2=Heissig |first2=Kurt |last3=Bebej |first3=Ryan M. |last4=von Koenigswald |first4=Wighart |date=28 June 2017 |title=Astragali of Pakicetidae and other early-to-middle Eocene archaeocetes (Mammalia, Cetacea) of Pakistan: locomotion and habitat in the initial stages of whale evolution |url=https://link.springer.com/article/10.1007/s12542-017-0362-8 |journal=[[PalZ]] |language=en |volume=91 |issue=4 |pages=601–627 |doi=10.1007/s12542-017-0362-8 |issn=0031-0220 |access-date=12 November 2024 |via=Springer Link|url-access=subscription }}</ref>