Ammosaurus

Name: Ammosaurus ‭(‬Sand lizard‭)‬.
Phonetic: Am-moe-sore-us.
Named By: Othniel Charles Marsh‭ ‬-‭ ‬1889.
Synonyms: Ammosaurus solus,‭ ‬Anchisaurus major,‭ ‬Anchisaurus solus.
Classification: Chordata,‭ ‬Reptilia,‭ ‬Dinosauria,‭ ‬Saurischia,‭ ‬Sauropodomorpha,‭ ‬Anchisauria.
Species: A.‭ ‬major‭ (‬type‭)‬.
Diet: Herbivore/Omnivore‭?
Size: 4‭ ‬meters long.
Known locations: Canada,‭ ‬Nova Scotia‭ ‬-‭ ‬McCoy Brook Formation.‭ ‬USA,‭ ‬Connecticut‭ ‬-‭ ‬Upper Portland Formation,‭ ‬Arizona‭ ‬-‭ ‬Navajo Sandstone.
Time period: Pliensbachian through to the Bajocian of the Jurassic.
Fossil representation: Partial post cranial remains of adult and juvenile specimens.

       Ammosaurus has a long taxonomic relationship with Anchisaurus.‭ ‬The holotype fossils of Ammosaurus were originally described as a large species of Anchisaurus by Othniel Charles Marsh before they were erected as a distinct genus.‭ ‬Marsh then named a new species of Anchisaurus,‭ ‬A.‭ ‬solus,‭ ‬but then attributed that to Ammosaurus.‭ ‬Later palaeontologists found that the A.‭ ‬solus remains were just those of a juvenile of Ammosaurus major,‭ ‬and so A.‭ ‬solus became a synonym to the type species.‭
       Around the end of the twentieth and beginning of the twenty-first centuries,‭ ‬fresh debate surrounded Ammosaurus with many prominent palaeontologists considering Ammosaurus to actually be synonymous with Anchisaurus.‭ ‬Others however pointed out subtle difference in the pelvis between Anchisaurus and Ammosaurus and continue to treat the two as separate genera,‭ ‬even though some have said that the differences are at a species level not a genus one.‭ ‬As such the validity of Ammosaurus as a distinct genus can vary greatly depending upon who you ask,‭ ‬but a safe statement is that the fossils from Ammosaurus and Anchisaurus,‭ ‬if not from the same genus of dinosaur,‭ ‬represent two that are very similar to one another in everything but size.
       I terms of being a dinosaur,‭ ‬Ammosaurus was a prosauropod dinosaur,‭ ‬the form that was the precursor to the huge quadrupedal sauropods that would become commonplace towards the later stages of the Jurassic.‭ ‬Ammosaurus may have been quadrupedal,‭ ‬but their lighter frames mean that they would have better been able to rear up on their hind legs to reach high vegetation.‭ ‬Prosauropods like Ammosaurus were also recently descended from meat eating ancestors back in the Triassic,‭ ‬and it is possible but currently unknown for sure if Ammosaurus occasionally ate meat as well as plants.‭ ‬This is not to say that Ammosaurus was an active predator,‭ ‬it may have simply supplemented its herbivorous diet by scavenging meat off the carcasses of other animals.‭ ‬With some remains of Ammosaurus dating to the Bajocian stage,‭ ‬Ammosaurus is one of the few prosauropods known to have survived into the late Jurassic.
       The wide geographical and temporal range of Ammosaurus means that it would have‭ ‬come into contact with many other early/mid Jurassic dinosaurs and other creatures.‭ ‬These included crocodyliforms like Protosuchus to predatory theropod dinosaurs like Dilophosaurus which may have been predators of Ammosaurus early on in the Jurassic.

Further reading
-‭ ‬The prosauropod dinosaur Ammosaurus,‭ ‬the crocodile Postosuchus,‭ ‬and their bearing on the age of the Navajo Sandstone of Northeastern Arizona,‭ ‬P.‭ ‬M.‭ ‬galton‭ ‬-‭ ‬1971.
-‭ A‬nchisaurus polyzelus‭ (‬Hitchcock‭)‬:‭ ‬the smallest known sauropod dinosaur and the evolution of gigantism among sauropodomorph dinosaurs,‭ ‬Adam M.‭ ‬Yates‭ ‬-‭ ‬2004.
-‭ ‬Description and evolutionary significance of the sauropodomorph dinosaurs from the early Jurassic‭ (‬Hettangian‭) ‬McCoy Brook Formation.‭ ‬Ph.D.‭ ‬dissertation.‭ ‬Halifax,‭ ‬Nova Scotia,‭ ‬T.‭ ‬J.‭ ‬Fedak‭ ‬-‭ ‬2007.
-‭ ‬A revision of the problematic sauropodomorph dinosaurs from Manchester,‭ ‬Connecticut and the status of Anchisaurus Marsh,‭ ‬Adam M.‭ ‬Yates‭ ‬-‭ ‬2010.



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