Where the decolonizers (colonizers??? ;) ) spell Paleo incorrectly and the women spell paleo correctly. Yay women! Sorry Marc, wish I was there and we could hang.

Cool photos!!!
Video of one of them fyi: www.instagram.com/reel/DHUdTyu...

Hey welcome to Bluesky @alec-wilken.bsky.social

Hey welcome to Bluesky @alec-wilken.bsky.social

This means that the temporal muscles of birds are more fore-aft oriented compared to the more vertical muscles of their dinosaur ancestors. This shows a change in feeding behaviors, from bitey, stiff skulls of early dinosaurs to dexterous, flexible-headed birds. Art by Corrine Cranor.

Meanwhile, we also project these vectors as ternary plots to get a general sense of orientation change. In general, you might see how many temporal muscle dots start at the top of the plot in Allosaurus and then plinko their way down along the RC (rostrocaudal) axis along the line to birds.

Meet our vector bouquets: orientations and magnitudes of jaw muscles projected as colored vectors and here plotted from a common origin on a single taxon, Dromaeosaurus, to show a phylogenetic change in muscle orientation.

The supplementary info hosts a number of plates documenting the muscle attachment sites we used to model jaw muscles. The centroids of each of these surfaces were used to estimate orientation vectors while the we also used them to model volumes which were used in estimating muscle forces.

Big ups to the group, particularly Alec Wilken and Kaleb Sellers for cooking up some simple yet elegant comparative approaches for exploring musculoskeletal biomechanics. Thanks to museum collections and colleagues for making specimens and their data available. Funding is thanks to #NSF.

Some birds use their protractor muscles to actively power cranial kinesis, but inferring this function in fossils is challenging. We compared 3D resultants of protractor muscles to orientations predicted palatal movement and found the muscles weren’t optimized for powering kinesis until Neognaths.

Compared to even their Cretaceous ancestors, living birds have fewer struts and linkages in their skulls, resulting in a higher potential for cranial kinesis, the ability of birds to move multiple joints in their skulls. Think about how a parrot can use its upper beak as an extra limb.

We reviewed palatal morphologies across a variety of Mesozoic birds. Many changes the palate occurred, namely the breakdown of linkages between the quadrate, epipterygoid and braincase. Much of this change maybe be hidden in the developmental biology of the palatoquadrate cartilage.

We figured out how to calculate 3D resultant vectors of jaw muscles in a modeled sample of living and extinct dinosaurs and found that a number of muscles change orientations and proportions as the brain got big and changed head shape during the origin of birds.

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biologicalsciences.uchicago.edu/news/bird-sk...