Pelecanimimus

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Pelecanimimus
Temporal range:
Ma
↓
Restoration of P. polyodon
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Clade: †Ornithomimosauria
Clade: †
Macrocheiriformes
Genus: †Pelecanimimus
Perez-Moreno et al., 1994
Species:
†P. polyodon
Binomial name
†Pelecanimimus polyodon
Perez-Moreno et al., 1994

Pelecanimimus (meaning "

theropod
), most of which were toothless.

Discovery and naming

In July 1993 Armando Díaz Romeral discovered a theropod skeleton at the Las Hoyas Unit 3 site. In 1994 this was named and described by Bernardino Pérez Pérez-Moreno, José Luis Sanz, Angela Buscalioni, José Moratalla, Francisco Ortega and Diego Rasskin-Gutman as a new species: Pelecanimimus polyodon. The generic name is derived from Latin pelecanus, "pelican", and mimus, "mimic", in reference to the long snout and throat pouch. The specific name is a reference to the large number of teeth possessed by this theropod and is derived from Greek πολύς (polys), "many" and ὀδούς (odous) "tooth".[1]

The

Calizas de La Huérguina Formation dating to the Lower Barremian
. The only known specimen consists of the articulated front half of a skeleton and includes the skull, lower jaws, all the neck vertebrae and most of the back vertebrae, ribs,
pectoral girdle, a complete right forelimb and most of the left forelimb. Remains of the soft parts are visible at the back of the skull, around the neck and around the front limbs.[1]

Description

Estimated size of Pelecanimimus, compared to a human.

Pelecanimimus was a small ornithomimosaur, at about 1.9–2.5 m (6.2–8.2 ft) and 17–30 kg (37–66 lb).

dentary. The teeth were heterodont, showing two different basic forms. The teeth in the front of the upper jaw were broad and D-shaped in cross-section, while those further back were blade-like, and on the whole the teeth in the upper jaw were larger than those in the lower. All of its teeth were unserrated, and had a constricted "waist" between the crown and the root. Interdental plates were lacking.[4]

Pelecanimimus being chased by Concavenator

Only one other ornithomimosaur is known to possess teeth, Harpymimus, which had far fewer (eleven total, and only in the lower jaw). The presence of such a large number of teeth in Pelecanimimus, coupled with a lack of interdental space, was interpreted by Pérez-Moreno et al. as an adaptation for cutting and ripping, a "functional counterpart of the cutting edge of a beak," as well as an exaptation leading to the toothless cutting edge found in later ornithomimosaurs.[1] The arms and hands of Pelecanimimus were more typical of ornithomimosaurs, with the ulna and radius bones in the lower arm tightly adhered to each other. The hand was hook-like and had fingers of equal length equipped with rather straight claws.[1]

Illustration of the skull from Pelecanimimus. The small crest in back of the head (colored in light grey) was probably made by keratin.

Soft-tissue remains preserved by the exceptional preservational environment of the La Hoyas lagerstätte revealed the presence of a small skin or keratin crest on the back of the head, and a

hyoid apparatus (specialized tongue bones in the neck).[1] Gregory S. Paul has speculated that Pelecanimimus might have been capable of flight or be a recent descendant from a flying animal.[6] This is due to the presence of large sternal plates and uncinate processes, which imply flight musculature. These adaptations have been noted years later by the paleontologist Mickey Mortimer.[7]

Classification

Pelecanimimus was by the describers assigned to the Ornithomimosauria, in the basalmost position.

troodontids) would be an adaptation for cutting and ripping. On the other hand, an excessive number of teeth with no interdental space (as in Pelecanimimus) would be a functional counterpart of the cutting edge of a beak. Thus, increasing the number of teeth would be an adaptation for cutting and ripping, as long as the space between adjacent teeth was preserved...while it would have the effect of working as a beak if spaces were filled with more teeth. The adaption to a cut-and-rip function therefore becomes an exaptation with a slicing effect, eventually leading to the cutting edge seen in most ornithomimosaurs."[1]

Cladogram after Kobayashi and Lü, 2003:[9]

Ornithomimosauria

Paleoecology

Pelecanimimus (foreground) among contemporary animals

The Las Hoyas lagerstätte has produced numerous other exquisitely preserved species, including the

crocodylomorphs are also known.[citation needed
]

See also

References

  1. ^
    doi:10.1038/370363a0
    .
  2. ^ Molina-Pérez & Larramendi (2016). Récords y curiosidades de los dinosaurios Terópodos y otros dinosauromorfos. Spain: Larousse. p. 268.
  3. OCLC 985402380
    .
  4. ^ Kobayashi, Y., and Barsbold, R. (2005). "Anatomy of Harpymimus okladnikovi Barsbold and Perle 1984 (Dinosauria; Theropoda) of Mongolia." in The Carnivorous Dinosaurs ed. Carpenter, K. 2005. Indiana University Press:97-126.
  5. ^ D. E. G. Briggs, P. R. Wilby, B. Pérez Pérez-Moreno, J. L. Sanz, M. Fregenal-Martinez, (1997). "The mineralization of dinosaur soft tissue in the Lower Cretaceous of Las Hoyas, Spain." Journal of the Geological Society of London, 154: 587-588.
  6. ^ Dinosaurs of the Air: The Evolution and Loss of Flight in Dinosaurs and Birds, pg 237
  7. ^ Did Dromiceiomimus really have long vaned secondaries?
  8. ^ Makovicky, P., Kobayashi, Y. and Currie, P. J. (2004). "Ornithomimosauria." pp. 137-150 in D. B. Weishampel, P. Dodson, et H. Osmólska (eds.), The Dinosauria. 2nd ed. University of California Press, Berkeley.
  9. ^ a b Kobayashi, Y., and Lü, J.-C. (2003). "A new ornithomimid dinosaur with gregarious habits from the Late Cretaceous of China." Acta Palaeontologica Polonica 48:235-259.

External links

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