Abundant Ornithischian Fossils afford ablaze on Late Cretaceous mega-fauna
With the alteration of abounding of the absent quarries aural the Anachronistic Provincial Park of Alberta added abstracts on the palaeocommunities from this arena has been collected. This has provided some arresting advice that may announce a assumption band of ornithischian genera (both ceratopsia and hadrosauridae) and advance to a greater compassionate of the blazon of habitats adopted by abounding types of dinosaur.
Between 1898 and 1954 about 40 ample palaeontological expeditions were beatific out into the Anachronistic Provincial Park abounding led by the acclaimed Charles Sternberg and his sons, accession building superior specimens for institutions such as the Royal Ontario museum, the American building of Natural History and the afresh British building (London Natural History museum). However, poor and abridged acreage affidavit as able-bodied as afield catalogued acreage photographs has led to a amount of these sites getting “lost”. The accelerated abrasion of the messas and buttes aural the bounded mural has added complicated the award of these deposit sites from just the accurate affirmation alone.
Researchers from the Royal Tyrrell building accept been arena detective and acquisition affirmation so that these old quarries can be amid and mapped application avant-garde all-around accession technology. Re-visiting these sites already they had been begin afresh has yielded added specimens and important micro-fossils, disregarded by the scientists during the aboriginal excavations. It is a acceptable job some palaeontologists are untidy, abounding of the sites accept been begin afresh as website debris depression accept been located. Dates if expeditions aboriginal visited a website accept been afflicted by belief old newspapers larboard abaft by the aboriginal scientists. During the aboriginal to mid allotment of the 20th Century, expeditions would backpack bundles of old newspapers with them to blanket fossils. Fragments of bi-weekly recovered from the depression and from about old quarries has helped the Royal Tyrrell aggregation to accurately date if these quarries were aboriginal explored.
Modern palaeontological techniques accept helped aftermath added finds and the sites accept been appropriately numbered and accurately recorded. This helped accommodate a clearer account of the changes in ambiance and the consistent fauna over the 2 actor years or so that the Anachronistic Park Formation represents (believed to awning 76 actor – 74 actor years ago).
Using this new advice and the stratigraphic administration of ornithischian dinosaurs, a time anatomy for above genera can be plotted. For example, no Chasmosaurines accept been begin in the Oldman Formation, but Chasmosaurs accept been begin in high Campanian sediments dating from 76 actor years ago, with Chasmosaurus russelli getting begin in the ancient strata with Chasmosaurus belli getting begin in afterwards strata, advertence a succession. Another ceratopsian group, the Centrosaurines are bedfast to a breadth of sediments about 40 metres abysmal dating from 76.5 mya to about 75 mya, afterwards this their abode in the deposit almanac seems to be taken by Styracosaurs.
A agnate arrangement of assumption can be apparent in the capital hadrosaur types about at the time if these sediments were laid down. In beforehand sediments, almost equating to the time of Centrosaurine ascendancy in the ceratopsia fauna, Corythosaurus genera dominate. These accord way to accretion numbers of Lambeosaurs such as Lambeosaurus magnicristatus.
This does not beggarly that the animals that preceded the afterwards ones are anon affiliated to them, but it ability announce that assertive genera were bigger able to acclimate to the alteration ambiance in this allotment of western North America during the closing stages of the Cretaceous. The Anachronistic Park Formation was deposited in the endure stages of the transgressive appearance of the Bearpaw cycle. Rising sea-levels would accept fabricated the breadth abundant added littoral and the altitude would accept been abundantly afflicted by the assailment of the sea. Perhaps the Centrosaurs and Corythosaurs were beneath able to acclimate to the alteration ambiance and adopted added civil habitats. This accustomed the Styracosaurs and the Lambeosaurs to move in and out attempt these added dinosaurs.
Ornithischian Faunal Zones aural high Campanian Stratigraphy of Alberta
74 mya – “Pachyrhinosaurid” – L. magnicristatus – C. irvinensis faunal zone?
Styracosaurus – Lambeosaurus faunal breadth C. belli
76 mya – Centrosaurus – Corythosaurus faunal breadth C. russelli
78 mya – New Centrosaurus Species No Chasmosaurines found
Ref: Anachronistic Provincial Park (Ecosystem Revealed) – P. J. Currie and E. B Koppelhus