Koparion

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Koparion
Temporal range:
Ma
↓
Holotype tooth
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Family: †Troodontidae
Genus: †Koparion
Chure, 1994
Type species
Koparion douglassi
Chure, 1994

Koparion is a

stage), of Utah
. It contains the single named species Koparion douglassi which is known only from a single isolated tooth.

Discovery

In 1993,

type specimen of the new species Koparion douglassi. The generic name Koparion comes from the Ancient Greek κοπάριον, "small surgical knife", in reference to the small size of the tooth. The specific name honors Earl Douglass, who, in the early twentieth century, excavated the Dinosaur National Monument quarry.[2]

The

Brushy Basin Member of the Morrison Formation dating from the late Kimmeridgian, about 151 million years old.[2] The taxon is thus present in stratigraphic zone 6 of the Morrison Formation.[3] The specimen consists of a single maxillary (upper cheek) tooth crown (the root is missing). It cannot be determined whether it represents a left or a right tooth.[2]

Description

life restoration

The tooth is two millimeters tall and very recurved, with a strongly convex front edge and a nearly vertical back edge. The tooth is stout, with a maximum fore-aft length of 1.9 millimeters. Both edges are serrated, showing low rectangular denticles (individual serrations). The twelve denticles on the rear edge are much higher than the fourteen on the front edge, which cover only the nearly horizontal upper part of the front edge. The tooth base, though very wide, is constricted. The base is asymmetrical, with the right side in front view protruding much further than the left side; because it is not known whether it is a left or right tooth, it cannot be established what is the inner and what the outer side. The denticles are separated by "blood grooves", and "blood pits" are also present. The back denticles point obliquely upwards but have no hooked upper corners.[2]

Classification

Chure assigned Koparion to the

temporal paradox argument, that such a close relationship were unlikely because the then oldest known bird, Archaeopteryx, lived much earlier than the Deinonychosauria, i.e. the Troodontidae and the Dromaeosauridae;[4] later also non-fragmentary Jurassic troodontid material was reported, from China.[5][6]

See also

References

  1. ^ Chure, D.J. and Britt, B.B., 1993, "New data on theropod dinosaurs from the Late Jurassic Morrison Fm. (MF)", Journal of Vertebrate Paleontology 13(3): 30A
  2. ^ a b c d e Chure, D. J. (1994). "Koparion douglassi, a new dinosaur from the Morrison Formation (Upper Jurassic) of Dinosaur National Monument; the oldest troodontid (Theropoda: Maniraptora)." Brigham Young University Geology Studies, 40: 11-15.
  3. ^ Foster, J. (2007). "Appendix." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. pp. 327–329.
  4. ^ Brochu, C.A., and Norell, M.A., 2000, "Temporal congruence and the origin of birds", Journal of Vertebrate Paleontology, 20: 197-200
  5. ^ Hu D., Hou L., Zhang L. and Xu X., 2009, "A pre-Archaeopteryx troodontid theropod from China with long feathers on the metatarsus", Nature 461: 640-643
  6. ^ Xu X., Ma Q. & Hu D., 2010, "Pre-Archaeopteryx coelurosaurian dinosaurs and their implications for understanding avian origins", Chinese Science Bulletin 55: 3971–3977
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