Editing Allosaurus (section)

==Paleoecology==

[[File:Alloquarrynolang.png|thumb|left|Locations in the [[Morrison Formation]] (yellow) where ''Allosaurus'' remains have been found]]
''Allosaurus'' was the most common large theropod in the vast tract of [[American West|Western American]] fossil-bearing rock known as the [[Morrison Formation]], accounting for 70 to 75% of theropod specimens,<ref name=JF07/> and as such was at the top [[trophic level]] of the Morrison food chain.<ref name=JRF03a>{{cite book |last=Foster |first=John R. |title=Paleoecological Analysis of the Vertebrate Fauna of the Morrison Formation (Upper Jurassic), Rocky Mountain Region, U.S.A. |year=2003 |series=New Mexico Museum of Natural History and Science Bulletin, '''23''' |publisher=New Mexico Museum of Natural History and Science |location=Albuquerque, New Mexico |page=29}}</ref> The Morrison Formation is interpreted as a [[semiarid]] environment with distinct [[wet season|wet]] and [[dry season]]s, and flat [[floodplain]]s.<ref name=DAR89>{{cite book |last=Russell |first=Dale A. |author-link=Dale Russell |title=An Odyssey in Time: Dinosaurs of North America |year=1989 |publisher=NorthWord Press |location=Minocqua, Wisconsin |isbn=978-1-55971-038-1 |pages=64–70 }}</ref> Vegetation varied from river-lining forests of [[conifer]]s, [[tree fern]]s, and [[fern]]s ([[gallery forest]]s), to fern [[savanna]]s with occasional trees such as the ''[[Araucaria]]''-like conifer ''[[Brachyphyllum]]''.<ref name=KC06>{{cite book |last=Carpenter |first=Kenneth |author-link=Kenneth Carpenter |year=2006 |chapter=Biggest of the big: a critical re-evaluation of the mega-sauropod ''Amphicoelias fragillimus'' |editor=Foster, John R. |editor2=Lucas, Spencer G. |title=Paleontology and Geology of the Upper Jurassic Morrison Formation |series=New Mexico Museum of Natural History and Science Bulletin, '''36''' |publisher=New Mexico Museum of Natural History and Science |location=Albuquerque, New Mexico |pages=131–138 }}</ref>

The Morrison Formation has been a rich fossil hunting ground. The flora of the period has been revealed by fossils of [[Chlorophyta|green algae]], fungi, [[moss]]es, [[Equisetum|horsetails]], ferns, [[cycad]]s, [[ginkgo]]es, and several families of [[conifer]]s. Animal fossils discovered include [[bivalve]]s, [[snail]]s, [[Actinopterygii|ray-finned fishes]], frogs, [[salamander]]s, turtles, [[Sphenodontia|sphenodont]]s, lizards, terrestrial and aquatic [[crocodylomorpha|crocodylomorphs]], several species of [[pterosaur]], numerous dinosaur species, and early [[mammal]]s such as [[Docodonta|docodont]]s, [[Multituberculata|multituberculate]]s, [[Symmetrodonta|symmetrodont]]s, and [[Triconodonta|triconodont]]s. Dinosaurs known from the Morrison include the theropods ''[[Ceratosaurus]]'', ''[[Ornitholestes]]'', ''[[Tanycolagreus]]'', and ''[[Torvosaurus]]'', the [[sauropod]]s ''[[Haplocanthosaurus]]'', ''[[Camarasaurus]]'', ''[[Cathetosaurus]]'', ''[[Brachiosaurus]]'', ''[[Suuwassea]]'', ''[[Apatosaurus]]'', ''[[Brontosaurus]]'', ''[[Barosaurus]]'', ''[[Diplodocus]]'', ''[[Supersaurus]]'', ''[[Amphicoelias]]'', and ''[[Maraapunisaurus]]'', and the [[ornithischia]]ns ''[[Camptosaurus]]'', ''[[Dryosaurus]]'', and ''[[Stegosaurus]]''.<ref name=DJCetal06>{{cite book |last1=Chure |first1=Daniel J. |last2=Litwin, Ron|last3= Hasiotis, Stephen T.|last4= Evanoff, Emmett|last5= Carpenter, Kenneth |year=2006 |chapter=The fauna and flora of the Morrison Formation: 2006 |editor=Foster, John R. |editor2=Lucas, Spencer G. |title=Paleontology and Geology of the Upper Jurassic Morrison Formation |series=New Mexico Museum of Natural History and Science Bulletin '''36''' |publisher=New Mexico Museum of Natural History and Science |location=Albuquerque, New Mexico |pages=233–248}}</ref> ''Allosaurus'' is commonly found at the same sites as ''Apatosaurus'', ''Camarasaurus'', ''Diplodocus'', and ''Stegosaurus''.<ref name="DBBM80">{{cite journal |last1=Dodson |first1=Peter |author-link1=Peter Dodson |last2=Behrensmeyer |first2=A.K. |last3=Bakker |first3=Robert T. |author-link3=Robert T. Bakker |last4=McIntosh |first4=John S. |year=1980 |title=Taphonomy and paleoecology of the dinosaur beds of the Jurassic Morrison Formation |journal=Paleobiology |volume=6 |issue=2 |pages=208–232 |doi=10.1017/S0094837300025768}}</ref> The Late Jurassic formations of Portugal where ''Allosaurus'' is present are interpreted as having been similar to the Morrison, but with a stronger [[Ocean|marine]] influence. Many of the dinosaurs of the Morrison Formation are the same genera as those seen in Portuguese rocks (mainly ''Allosaurus'', ''Ceratosaurus'', ''Torvosaurus'', and ''Stegosaurus''), or have a close counterpart (''Brachiosaurus'' and ''[[Lusotitan]]'', ''Camptosaurus'' and ''[[Draconyx]]'').<ref name=OM06>{{cite book |last=Mateus |first=Octávio |year=2006 |chapter=Jurassic dinosaurs from the Morrison Formation (USA), the Lourinhã and Alcobaça Formations (Portugal), and the Tendaguru Beds (Tanzania): A comparison |editor=Foster, John R. |editor2=Lucas, Spencer G. |title=Paleontology and Geology of the Upper Jurassic Morrison Formation |series=New Mexico Museum of Natural History and Science Bulletin, '''36''' |publisher=New Mexico Museum of Natural History and Science |location=Albuquerque, New Mexico |pages=223–231}}</ref>

[[File:Dry season at the Mygatt-Moore Quarry.PNG|thumb|alt=Allosaurus and Ceratosaurus fighting|Dry season at the Mygatt-Moore Quarry showing ''Ceratosaurus'' (center) and ''Allosaurus'' fighting over the desiccated carcass of another theropod]]
''Allosaurus'' coexisted with fellow large theropods ''[[Ceratosaurus]]'' and ''[[Torvosaurus]]'' in both the United States and Portugal.<ref name=OM06/> The three appear to have had different [[ecological niche]]s, based on anatomy and the location of fossils. ''Ceratosaurus'' and ''Torvosaurus'' may have preferred to be active around waterways, and had lower, thinner bodies that would have given them an advantage in forest and underbrush terrains, whereas ''Allosaurus'' was more compact, with longer legs, faster but less maneuverable, and seems to have preferred dry floodplains.<ref name=BB04>{{cite book |last1=Bakker |first1=Robert T. |last2=Bir, Gary |year=2004 |chapter=Dinosaur crime scene investigations: theropod behavior at Como Bluff, Wyoming, and the evolution of birdness |editor=Currie, Philip J. |editor2=Koppelhus, Eva B. |editor3=Shugar, Martin A. |editor4=Wright, Joanna L. |title=Feathered Dragons: Studies on the Transition from Dinosaurs to Birds |publisher=Indiana University Press |location=Bloomington and Indianapolis |pages=301–342 |isbn=978-0-253-34373-4}}</ref> ''Ceratosaurus'', better known than ''Torvosaurus'', differed noticeably from ''Allosaurus'' in functional anatomy by having a taller, narrower skull with large, broad teeth.<ref name=DH98/><!--if anyone finds the ref where ''Allosaurus'' was suggested as a female ''Ceratosaurus'', here's a good place to put it for irony--> ''Allosaurus'' was itself a potential food item to other carnivores, as illustrated by an ''Allosaurus'' [[Pubis (bone)|pubic foot]] marked by the teeth of another theropod, probably ''[[Ceratosaurus]]'' or ''[[Torvosaurus]]''. The location of the bone in the body (along the bottom margin of the torso and partially shielded by the legs), and the fact that it was among the most massive in the skeleton, indicates that the ''Allosaurus'' was being scavenged.<ref name=CFJ98>{{cite journal |last=Chure |first=Daniel J. |year=2000 |title=Prey bone utilization by predatory dinosaurs in the Late Jurassic of North America, with comments on prey bone use by dinosaurs throughout the Mesozoic |journal=Gaia |volume=15 |pages=227–232 |issn=0871-5424 |url=https://www.academia.edu/18277086 |archive-date=November 9, 2021 |access-date=December 4, 2017 |archive-url=https://web.archive.org/web/20211109012826/https://www.academia.edu/18277086 |url-status=live }}</ref>

A bone assemblage in the Upper Jurassic Mygatt-Moore Quarry preserves an unusually high occurrence of theropod bite marks, most of which can be attributed to ''Allosaurus'' and ''Ceratosaurus'', while others could have been made by ''Torvosaurus'' given the size of the striations. While the position of the bite marks on the herbivorous dinosaurs is consistent with predation or early access to remains, bite marks found on ''Allosaurus'' material suggest scavenging, either from the other theropods or from another ''Allosaurus''. The unusually high concentration of theropod bite marks compared to other assemblages could be explained either by a more complete utilization of resources during a dry season by theropods, or by a collecting bias in other localities.<ref>{{Cite journal|last1=Drumheller|first1=Stephanie K.|last2=McHugh|first2=Julia B.|last3=Kane|first3=Miriam|last4=Riedel|first4=Anja|last5=D’Amore|first5=Domenic C.|date=May 27, 2020|title=High frequencies of theropod bite marks provide evidence for feeding, scavenging, and possible cannibalism in a stressed Late Jurassic ecosystem|journal=PLOS ONE|language=en|volume=15|issue=5|pages=e0233115|doi=10.1371/journal.pone.0233115|issn=1932-6203|pmc=7252595|pmid=32459808|bibcode=2020PLoSO..1533115D|doi-access=free}}</ref>