Aerosteon
Aerosteon Temporal range:
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Skeletal diagram illustrating air-filled bones | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | Saurischia |
Clade: | Theropoda |
Clade: | †Megaraptora |
Family: | †Megaraptoridae |
Genus: | †Aerosteon Sereno et al. 2009 |
Type species | |
†Aerosteon riocoloradensis Sereno et al. 2009
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Aerosteon is a
They show evidence of a bird-like respiratory system.[1] Aerosteon's name can be translated as air bone and derives from Greek ἀήρ (aer, "air") and ὀστέον (osteon, "bone").
Discovery
Aerosteon was first discovered in 1996 and was first described by Sereno et al. in a paper which appeared in the online journal PLoS ONE in September 2008. However, at the time, the International Code of Zoological Nomenclature did not recognize online publication of names for new species as valid unless print copies were also produced and distributed to several libraries, and that this action is noted in the paper itself. PLoS ONE initially failed to meet this requirement for Aerosteon. On May 21, 2009, the journal's managing editor coordinated with the ICZN to correct this oversight, publishing a comment to the original paper with an addendum stating that the requirements had been met as of that date. Consequently, though the description appeared in 2008, Aerosteon was not a valid name until 2009.[2]
The
Description
Initially Aerosteon was estimated at 9 to 10 meters (30 to 33 ft).[1] In 2010, however, Gregory S. Paul, estimated it at 6 meters (20 ft) and 500 kilograms (1,100 lb).[4] Later in 2016, Molina-Pérez and Larramendi gave a length of 7.5 meters (25 ft) and a weight of 1 metric ton (1.1 short tons).[5]
Classification
Aerosteon did not initially appear to belong to any of the three groups of large theropods that were known to have inhabited the
A very close relative of Aerosteon, Murusraptor, was described in 2016 which preserved some bones with a lesser level of pneumaticity. However, the Murusraptor holotype also preserved several teeth which were very dissimilar to the one tooth observed in Aerosteon's holotype. The authors of the description noted that this tooth closely resembled that of abelisaurids and was probably incorrectly referred to Aerosteon. Murusraptor and Aerosteon are practically identical in the structure of their cranial bones and vertebrae, only noticeably differing in the proportions of the ilium, with Aerosteon's ilium being taller than that of Murusraptor.[10]
The cladogram below follows the 2010 analysis by Benson, Carrano and Brusatte, which considered megaraptorans as tetanurans.[6]
Neovenatoridae |
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The cladogram shown below follows an analysis by Porfiri et al., 2014, which recovered megaraptorans as tyrannosauroids.[11]
Megaraptora |
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Paleobiology
Some of Aerosteon's bones show pneumatization (air-filled spaces), including pneumatic hollowing of the furcula and ilium, and pneumatization of several gastralia. The addition of pneumatization throughout the bones of Aerosteon shows the evolutionary progress of the avian air sacs, which first appear as features on the sides of vertebrae, before being incorporated within bones throughout the skeleton. These air sacs would have acted like bellows, moving air into and out of the animal's relatively inflexible lungs, instead of the lungs themselves being expanded and contracted as occurs with
Sereno et al. theorize that this respiratory system may have developed to assist with regulating body temperature and was later co-opted for breathing.[1]
Paleoecology
Aerosteon lived approximately 84 million years ago during the
References
- ^ PMID 18825273.
- ^ PLoS ONE Group (2009). "Steps taken to meet the requirements of the ICZN to make new taxonomic names nomenclaturally available. Archived December 5, 2022, at the Wayback Machine" Comment on Original Article: "Evidence for Avian Intrathoracic Air Sacs in a New Predatory Dinosaur from Argentina." PLoS ONE, May 21, 2009.
- from the original on September 16, 2020. Retrieved September 15, 2020.
- ^ Paul, Gregory S. (2010). The Princeton Field Guide to Dinosaurs. New Jersey: Princeton University Press. p. 99.
- ^ Molina-Pérez & Larramendi (2016). Récords y curiosidades de los dinosaurios Terópodos y otros dinosauromorfos. Spain: Larousse. p. 264.
- ^ S2CID 22646156.
- ^ F. E. Novas; F. L. Agnolín; M. D. Ezcurra; J. I. Canale; J. D. Porfiri (2012). "Megaraptorans as members of an unexpected evolutionary radiation of tyrant-reptiles in Gondwana". Ameghiniana. 49 (Suppl): R33. Archived from the original on March 11, 2016. Retrieved December 2, 2013.
- PMID 27410683.
- hdl:11336/48895.
- PMID 27439002.
- hdl:11336/12129.