Wednesday, 6 May 2015

Romer’s Gap tetrapods of Nova Scotia

Last week the first paper from the TW:eed Project was published, on the tetrapods of Horton Bluff, Nova Scotia. The Nova Scotia fossils are the same age as specimens from the Scottish Borders, from the period known as Romer’d Gap. The paper is the first to show that Romer’s Gap may not be a not a true gap in the tetrapod fossil record, but it may be instead caused by biases in fossil collection. 

For decades, isolated fossil bones have been collected from a locality called Blue Beach at Horton Bluff, Nova Scotia. These new specimens have enabled researchers to identify that a diverse tetrapod fauna was present. The paper describes three distinct forms of humerus, two of scapulo-coracoid (part of the shoulder girdle), four of femur, two of tibia and two of pelvis. Although isolated, the shapes of some of these bones are fairly distinctive, allowing the authors to estimate taxonomic diversity at the locality. They conclude that there are at least five different types of tetrapod represented, and can infer the presence of several more, based on the extensive sets of trackways which have been collected over the years. 
Tetrapod femur (leg) bones illustrated in the publication

The Blue Beach fauna includes some tetrapods clearly similar to some of the Late Devonian forms, as well as animals more similar to those that appear later in the Carboniferous. This means that some tetrapods survived the end Devonian mass extinction event. This study is the first to illuminate what tetrapod communities looked like in the early Carboniferous and is a great first result for the TW:eed Project.

The lead author on the paper is Jason Anderson from the University of Calgary, along with Tim Smithson and Jenny Clack, and Canadian colleagues Chris Mansky and Taran Meyer. The article is called ‘A Diverse Tetrapod Fauna at the Base of 'Romer'sGap'’ and is published in the journal PLOS ONE, which is online and open access, clicking the link with the article title to view it. You can read more about the results of the study on the TW:eed website, and see a video of the field site. 

Until next time

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