A New Take on the Dinosaur Phylogenetic Tree

Contributed by Alli Weis

This week’s blog post is inspired by a new hypothesis that has emerged this month, published in the journal Nature. Essentially, for years the widely accepted theory of Dinosaur relationships has been based on dividing Dinosaurs into two main categories. The division was based upon the hips, or the pelvic anatomy. One category was classified as “bird-like”, known as Ornithischia and the other being “lizard-like” and known as Saurischia. For nearly a century now, the two groups have been classified as separate and thought to have two distinctly different ancestors lineages. This new study has found evidence for another option. They say that they have found a sister-group relationship between Ornithischia (bird-like pelvis) and Theropoda, and named that group “Ornithoscelida”. Further, Sauropodomorpha and Herrerasauridae are now in a refined grouping of Saurischia.

What this means is that now tens of dinosaur scientists (perhaps hundreds? How many are there?) are currently pouring over the data, reanalyzing it and coming up with rebukes to this new controversial theory. Science! Importantly it is a great example for the need to always challenge the central dogma in any field, and, as new molecular data emerges and new computer programs are developed to assist in the analysis and interpretation of data, it’s important to challenge old theories and hypotheses of the past. Somewhere along the road we stumble upon the truth.

Here is the paper:

http://www.nature.com/nature/journal/v543/n7646/full/nature21700.html

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