Basilosauridae

Basilosauridae is a paraphyletic family of extinct cetaceans that lived during the late middle to the early late Eocene,[2] known from all continents including Antarctica.[1][3] They were probably the first fully aquatic cetaceans.[2]

Basilosauridae
Temporal range: Late Eocene, 45–33.9 Ma [1]
Saghacetus osiris
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Infraorder: Cetacea
Family: †Basilosauridae
Cope 1868[1]
Genera

See text

Taxonomy

Basilosaurinae was proposed as a subfamily containing two genera: Basilosaurus and Basiloterus.[4] They were characterized by elongated distal thoracic vertebrae, lumbar, and proximal sacrococcygeal. All known members of the subfamily are larger than their relatives of the Dorudontinae subfamily except Cynthiacetus.[5] It was declared an invalid subgroup of Basilosauridae by Uhen 2013.[4]

Characteristics
Dorudon atrox skeleton

Basilosaurids ranged in size from 4 to 16 m (13 to 52 ft). Like all archaeocetes, they lacked the telescoping skull of modern whales. Their dentition is easily distinguishable from that of other archaeocetes: they lack upper third molars and the upper molars lack protocones, trigon basins, and lingual third roots. The cheek teeth have well-developed accessory denticles. The hindlimbs are strongly reduced and does not articulate with the vertebral column which lack true sacral vertebrae.[2]

Basilosaurid forelimbs have broad and fan-shaped scapulae attached to a humerus, radius, and ulna which are flattened into a plane to which the elbow joint was restricted, effectively making pronation and supination impossible. Because of a shortage of forelimb fossils from other arachaocetes, it is not known if this arrangement is unique to basilosaurids. Some of the characteristics of basilosaurids are also present in Georgiacetus.[2]The overall long serpentine body shape of Basilosaurids show signs of convergent evolution with mosasaurs which suggests that this body plan seems to have been rather successful.[6]

Systematics
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gollark: 1. random mistreated boy turns out to be magic, goes to boarding school, kills professor with fire (insane headmaster explains it as his mother's love)2. boy talks to snakes, kills an endangered species, kills professor again3. boy helps fugitive who escaped from wizard prison, breaks out dangerous animal, meddles with the laws of time itself4. boy is entered in ridiculously dangered banned tournament allegedly against his will, unwillingly resurrects professor5. boy participates in secret rebel group or whatever, I forgot6. ???, potions, ???, unethically manipulates professor via probability fiddling maybe7. boy becomes fugitive, re-kills professor, dies, un-dies, etc.
gollark: The summarizing or the reading it?
gollark: I'm pretty sure it cannot be evited.
gollark: Anyway, I read Harry Potter a few times so I can probably summarize it to you.

See also

Notes
  1. Basilosauridae in the Paleobiology Database
  2. Uhen 2002
  3. Fostowicz-Frelik 2003
  4. Basilosauridae in the Paleobiology Database. Retrieved July 2013.
  5. Uhen 2008
  6. Oceans of Kansas: a Natural History of the Western Interior Sea. Indiana University Press. ISBN 9780253345479.

References


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