Hanson Formation

Hanson Formation
Stratigraphic range: Hettangian-Pliensbachian
~196.5–183 Ma
Type Geological formation
Unit of Victoria Group
Sub-units Three informal members
Underlies Prebble Formation
Overlies Falla Formation
Thickness 237.5 m (779 ft)
Lithology
Primary Sandstone, tuffite
Location
Coordinates 84°18′S 166°30′E / 84.3°S 166.5°E / -84.3; 166.5Coordinates: 84°18′S 166°30′E / 84.3°S 166.5°E / -84.3; 166.5
Approximate paleocoordinates 57°30′S 35°30′E / 57.5°S 35.5°E / -57.5; 35.5
Region Mount Kirkpatrick, Beardmore Glacier
Country  Antarctica

The Hanson Formation is a geologic formation on Mount Kirkpatrick, Antarctica. It is one of only two major dinosaur-bearing rock formations found on the continent of Antarctica to date; the other is the Santa Marta Formation from the Late Cretaceous. The formation has yielded only a handful of Mesozoic specimens so far and most of it is as yet unexcavated. Part of the Victoria Group of the Transantarctic Mountains, it is below the Prebble Formation and above the Falla Formation.[1]

Paleofauna

The first dinosaur to be discovered from the Hanson Formation was the predator Cryolophosaurus in 1991, which was then formally described in 1994. Alongside these dinosaur remains were fossilized trees, suggesting that plant matter had once grown on Antarctica's surface before it drifted southward. Other finds from the formation include tritylodonts, herbivorous mammal-like reptiles and crow-sized pterosaurs. Surprisingly were the discovery of prosauropod remains, which were found commonly on other continents only until the Early Jurassic. However, the bone fragments found at the Hanson Formation were dated until the Middle Jurassic, millions of years later. In 2004, paleontologists discovered partial remains of a large sauropod dinosaur that has not formally been described yet.

Bony fish

Bony fishes of the Hanson Formation
Genus Species Location Stratigraphic position Material Notes Images

Oreochima

O. ellioti

A archaeomaenid pachycormiform fish.

Invertebrate paleofauna

Insects of the Hanson Formation
Genus Species Location Stratigraphic position Material Notes Images

Ademosynoides

A. antarcticus

A False Ground Beetle.

Grahamelytron

G. crofti

A Beetle.

Dinosaurs

The following dinosaur fossils have been found in the formation:[2]

Color key
Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
 Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.
Dinosaurs of the Hanson Formation
Genus Species Province Stratigraphic position Material Notes Images

Heterodontosauridae[3]

Indeterminate[2]

"Vertebrae, femur and possible caudal vertebrae."

Glacialisaurus[4]

G. hammeri [2]

"A partial right astragalus, medial and lateral distal tarsals, and partial right metatarsus preserved in articulation with each other."

A 8m long Massospondyloid
GlacialisaurusHolotype foot

Sauropoda[4][5]

Indeterminate[2][5]

The presence of Glacialisaurus in the Hanson Formation with advanced true sauropods shows that both primitive and advanced members of this lineage existed side by side in the early Jurassic Period.[4][6][5]

Coelophysidae? [2]

Indeterminate[2]

Cryolophosaurus[2]

C. ellioti[2]

"Partial skull and partial postcranium."[7]
Cryolophosaurus

Pterosaurs

Pterosaurs of the Hanson Formation
Genus Species Location Stratigraphic position Material Notes Images

Dimorphodon?

Indeterminate

Humerus
Dimorphodon

Synapsids

Synapsids of the Hanson Formation
Genus Species Location Stratigraphic position Material Notes Images

Tritylodon?

Indeterminate

"FMNH PR1824, an isolated upper postcanine tooth."

Tritylodon was a species of tritylodont, one of the most advanced group of cynodonts. It was small in size and had an herbivorous diet, something of an anomaly among the mostly carnivorous cynodonts. Tritylodon had many features of modern mammals, but was egg-laying.
Tritylodon

See also

References

  1. ↑ Elliot, D.H. (1996). The Hanson Formation: a new stratigraphical unit in the Transantarctic Mountains, Antarctica. Antarctic Science 8(4):389-394.
  2. 1 2 3 4 5 6 7 8 Weishampel, David B; et al. (2004). "Dinosaur distribution (Early Jurassic, Asia)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. p.537. ISBN 0-520-24209-2.
  3. ↑ Hammer adds another new dinosaur to his collection: https://augustana.net/x33229.xml
  4. 1 2 3 Smith, Nathan D.; Pol, Diego (2007). "Anatomy of a basal sauropodomorph dinosaur from the Early Jurassic Hanson Formation of Antarctica" (pdf). Acta Palaeontologica Polonica. 52 (4): 657–674.
  5. 1 2 3 Pickrell, John (2004). "Two New Dinosaurs Discovered in Antarctica". National Geographic. Retrieved 20 December 2013.
  6. ↑ Smith, N.D., Makovicky, P.J., Pol, D., Hammer, W.R., and Currie, P.J. (2007). "The Dinosaurs of the Early Jurassic Hanson Formation of the Central Transantarctic Mountains: Phylogenetic Review and Synthesis" (PDF). U.S. Geological Survey and the National Academies. 2007 (1047srp003): 5 pp. doi:10.3133/of2007-1047.srp003.
  7. ↑ "Table 4.1," in Weishampel, et al. (2004). Page 74.
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