Pelecanimimus
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 Life restoration of head and neck of Pelecanimimus polyodon.
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Extinct (fossil)
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| Pelecanimimus polyodon Perez-Moreno et al., 1994 |
Pelecanimimus is a basal ornithomimosaur from the Early Cretaceous of Spain. This taxon is notable for possessing more teeth than any other member of the Ornithomimosauria, most of which were toothless. The holotype specimen (LH 777, Museo de Cuenca, Cuenca, Spain) consists of the articulated anterior half of a skeleton and includes the skull, the entire cervical and most of the dorsal vertebral series, ribs, sternum, the pectoral girdle, a complete right forelimb and most of the left forelimb. It was recovered at the famous La Hoyas locality in Cuenca Province, Spain, from lagerstätte beds within the Calizas de La Huérguina Formation (Lower Barremian). This same lagerstätte has produced numerous other exquisitely preserved taxa, including the enantiornithine birds Iberomesornis, Concornis, and Eoalulavis, along with non-avian theropod teeth and a few fragmentary sauropod bones. Lateral detrital facies of the La Hoyas lagerstätte has produced bones of the ornithopod dinosaur Iguanodon. The lagerstätte beds have also yielded remains of lizards and salamanders. The etymology of the genus name derives from the long facial part of the skull and integumentary impressions associated with the skull, resembling the gular pouch of the modern-day pelican (Latin Pelecanus = pelican + Greek mimus = mimic). The species is named for the large number of teeth possessed by this theropod (Greek polys = "many" + Greek odus = teeth).
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[edit] Diagnosis and Morphology
Pérez-Moreno et al. (1994, p.364) diagnose Pelecanimimus as follows: "Small ornithomimosaur (2-2.5 m long). Skull with long and shallow snout (maximum length about 4.5 times the maximum height). About 220 teeth: 7 premaxillary, about 30 maxillary, and 75 in the dentary. Heterodont. Maxillary teeth larger than dentary teeth. Teeth unserrated, with a constriction between the crown and the root. There are no complete interdental plates. The maxilla has teeth only in its anterior third, and a sharp edge in the posterior zone. The rostral half of the lower jaw has a straight ventral edge. Ulna and radius are tightly adhered distally. Metacarpal ratio is 0.81:1:0:98." Only one other ornithomimosaur is known to possess teeth, Harpymimus, which has far fewer (eleven total, and only in the dentary). The presence of such a large number of teeth in Pelecanimimus, coupled with a lack of interdental space, has been interpreted (Pérez-Moreno et al., 1994: p.366; see below) 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 members of the clade. The snout is very long and shallow. A small prominence on the dorsal part of the lacrimal indicates the presence of minute lacimal horns. Soft-tissue impressions preserved by the exceptional preservational environment of the La Hoyas lagerstätten reveal the presence of an occipital crest, the aforementioned gular pouch, and smooth skin lacking any ornamentation or feathers. Pelecanimimus was the first ornithomimosaur discovered with a preserved hyoid apparatus.
[edit] Phylogeny and Evolution
Cladistic analyses indicate that Pelecanimimus is the basalmost member of the Ornithomimosauria (Makovicky et al., 2005: p. 148), less derived even than Harpymimus. These two taxa form a basal arrangement of (Pelecanimimus [Harpymimus (Garudimimus + Ornithomimidae)] (Kobayashi and Lü, 2003). The discovery of Pelecanimimus has played an important and surprising role in understanding the evolution of the Ornithomimosauria. To quote Pérez-Moreno et al. (1994, pp.365-366): "The phylogenetic hypothesis...supports an unexpected approach, involving exaptation, which might explain the evolutionary process towards the toothless condition in Ornithomimosauria. Until now, a progressive reduction in the number of teeth has been considered as the most likely explanation: the primitive tetanurine theropods have up to 80 teeth with tall blade-like crowns, and the primitive ornithomimosaurs have only a few small teeth. The phylogenetic hypothesis suggests an alternative evolutionary process based on a functional analysis of increasing numbers of teeth. A high number of teeth with enough interdental space and properly placed denticles (as in 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."
[edit] In popular culture
Pelecanimimus is in the game Dino Island.
[edit] References
- Kobayashi, Y. et 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.
- Kobayashi, Y. et Lü, J.-C. 2003. A new ornithomimid dinosaur with gregarious habits from the Late Cretaceous of China. Acta Palaeontologica Polonica 48:235-259.
- 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.
- Perez-Moreno, B. P., Sanz, J. L., Buscalioni, A. D., Moratalla, J. J., Ortega, F., et Raskin-Gutman, D. 1994. A unique multitoothed ornithomimosaur from the Lower Cretaceous of Spain. Nature 30:363-367.
