''Attockicetus'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus of remingtonocetid early whale known from the

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

(

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 ...

)

Kuldana Formation The Kuldana Formation is a fossil-bearing geological formation of Lutetian (Early Eocene) age which outcrop, crops out in northern Pakistan. The abundant fossil remains were deposited by rivers and estuaries crossing an arid to semi-arid enviro ...

in the Kala Chitta Hills, in the

Attock District Attock District ( Punjabi/Urdu), known as Campbellpur District during British Raj, is a district, located on the Pothohar Plateau, in north western Punjab, Pakistan; created in April 1904. According to 2023 Pakistani census population of Att ...

Punjab, Pakistan Punjab (, ) is a Administrative units of Pakistan, province of Pakistan. With a population of over 127 million, it is the Demographics of Pakistan, most populous province in Pakistan and the List of first-level administrative divisions by popu ...

. ''Attockicetus'' is described based on fragmentary cranial material. The

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

specimen, H-GSP 96232, includes a fragmentary

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 ...

, an

endocast An endocast is the internal cast of a hollow object, often referring to the cranial vault in the study of brain development in humans and other organisms. Endocasts can be artificially made for examining the properties of a hollow, inaccessible ...

(interior of cranium), and an

ectotympanic The ectotympanic, or tympanicum, is a bony structure found in all mammals, located on the tympanic part of the temporal bone, which holds the tympanic membrane (eardrum) in place. In catarrhine primates (including humans), it takes a tube-shape. ...

(ear bone). The specimen also had preserved cheek teeth, P³-M³, which is rare in remingtonocetids. ''Attockicetus'' is primitive in the retention of large protocones on the upper molars and the location of the

orbits In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an physical body, object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an satellite, artificia ...

anteriorly on the skull. It is probably the most

plesiomorphic In phylogenetics, a plesiomorphy ("near form") and symplesiomorphy are synonyms for an ancestral character shared by all members of a clade, which does not distinguish the clade from other clades. Plesiomorphy, symplesiomorphy, apomorphy, an ...

remingtonocetid. Additional dental material was found at the type locality and assigned to ''Attockicetus''. Compared to pakicetid teeth found at the same locality, the P₃ of ''Attockicetus'' is much lower, angled anteriorly, and has a very long posterior extension. A long

diastema A diastema (: diastemata, from Greek , 'space') is a space or gap between two teeth. Many species of mammals have diastemata as a normal feature, most commonly between the incisors and molars. More colloquially, the condition may be referred to ...

separates P₃ from P₄ and P₃ is longer than P₄, which was identified as a remingtonocetid character and, because ''Attockicetus'' is the only known remingtonocetid known from the Kala Chitta Hills, they tentatively assigned the specimen as belonging to this genus. The P₄ of ''Attockicetus'' is similar to those of ''Pakicetus'' in retaining a tall protoconid (cusp) and anterior and posterior basal extensions with prominent cristae (crests), but differs from them in having steeper protoconid slopes, being taller, and having longer basal extensions. The molar wear in pakicetids is typically extensive, whilst the P₄ in ''Attockicetus'' is less worn, suggesting that the latter was not used for breaking down food, but for holding prey.

Notes

References

* * {{Taxonbar, from=Q871300 Remingtonocetidae Fossil taxa described in 2000 Monotypic prehistoric cetacean genera Extinct mammals of Asia

See also

Notes

References