Paleonews

Il blog dedicato ai Paleontologi !!!!

2008-10-22 – Nuove ipotesi su migrazione dei Dinosauri polari (Polar dinosaurs, migration)

Uno studio condotto con un approccio di tipo fisiologio (ad es. energia necessaria) ha evidenziato che non tutti i dinosauri erano in grado di sostenere lunghe migrazioni da e verso i poli, ritenendo dunque plausibile che essi fossero invece adattati alla vita e al clima alle basse latitudini.

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Polar dinosaurs may have taken shorter treks

Phil Bell holding a vertebra of a 70-million-year-old Saurolophus.

October 21, 2008 – Edmonton-Contrary to popular belief, polar dinosaurs may not have traveled nearly as far as originally thought when making their bi-annual migration.

University of Alberta researchers Phil Bell and Eric Snively have suggested that while some dinosaurs may have migrated during the winter season, their range was significantly less than previously thought, which means their treks were shorter. Bell and Snively’s findings were recently published in Alcheringa: An Australasian Journal of Paleontology.

The idea that these animals may have travelled distances nine times further than mule deer or four times those of wildebeest would have made them the greatest migrators in history. “There are strong opinions regarding dinosaur migration, but we decided to take a different approach, looking at variables such as energy requirements,” said Bell. Their research led them to suggest that migrating dinosaurs could have travelled up to 3,000 kilometres in a round trip-lasting perhaps up to six months-half of the distance suggested previously.

According to Bell, the notion of migrating polar dinosaurs is not new; however, previously-held beliefs were that the animals followed the centrally shifting sunlight, or latitudinal “sun line,” as part of their migration and would travel as far as 30 degrees of latitude, or 3,200 kilometres, in order to survive. Given their size and physiology, Bell and Snively have concluded that dinosaurs would have been incapable of sustaining the effort needed to make the trip. “When we looked at the energy requirements needed to support a three-tonne Edmontosaurus over this distance, we found it would have to be as energy efficient as a bird. No land animal travels that far today,” said Bell.

Bell does not dispute the evidence of migration and points to discoveries of large bone beds as evidence that many dinosaurs also traveled. In order to sustain the herd, “it seemed to make sense that they would be moving to and from the poles,” he said.

While this view of migration is feasible for some species of polar dinosaurs, it does not hold for all, Bell noted. “Many types of dinosaurs were surviving in polar latitudes at the time, and getting along quite fine,” said Bell. “They were not physically able to remove themselves from the environment for a variety of reasons and had to adapt to the cold, dark winters just as the rest of us mammals do today.”

 Related Internal Links

University of Alberta Department of Biological Sciences:
http://www.biology.ualberta.ca/

source: http://www.expressnews.ualberta.ca/article.cfm?id=9693
Other links: http://www.sciencedaily.com/releases/2008/10/081021185205.htm
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original article:
Alcheringa: An Australasian Journal of Palaeontology, Volume 32 Issue 3 2008 271 – 284
Authors: Phil R. Bell; Eric Snively
DOI: 10.1080/03115510802096101

Abstract

Cretaceous polar dinosaur faunas were taxonomically diverse, which suggests varied strategies for coping with the climatic stress of high latitudes. Some polar dinosaurs, particularly larger taxa such as the duckbill Edmontosaurus Lambe, 1917, were biomechanically and energetically capable of migrating over long distances, up to 2600 km. However, current evidence strongly suggests many polar dinosaurs (including sauropods, large and small theropods, and ankylosaurs of New Zealand) overwintered in preference to migration. Certain groups also appear more predisposed to overwintering based on their physical inability (related to biomechanics, natural history, or absolute size) to migrate, such as ankylosaurs and many small taxa, including hypsilophodontids and troodontids. Low-nutrient subsistence is found to be the best overwintering method overall, although the likelihood that other taxa employed alternative means remains plausible. Despite wide distribution of some genera, species-level identification is required to assess the applicability of such distributions to migration distances. Presently, such resolution is not available or contradicts the migration hypothesis.
Keywords: Alaska; Albian; Aptian; Australia; Campanian; Cretaceous; Dinosaur Cove; endothermy; migration; New Zealand; polar dinosaurs

ottobre 22, 2008 - Posted by | - R. Dinosauri, 1 Cretaceo, America Northern, Antartide, Articolo sc. di riferimento, Oceania, P - Paleoetologia, Paleontology / Paleontologia | , , , , , , , , , , ,

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