Research

Simulating Morphology with SlicerMorph and Advanced Normalization Tools (ANTs)

Interpreting the results of discovery-oriented exploratory analyses can be challenging because the expected outcomes are not known ahead of time. If no differences are detected between groups, does it mean there really is no difference, or does it reflect a problem with your study design? In this preprint, we present a new method for morphological simulation using open-access, open source tools in 3D Slicer, SlicerMorph, and R, and demonstrate how this method can be used to test the limits on phenotype discovery. 

To learn more, click here.

Top: dorsal views of four fetal porpoise skull CT scans and one fetal Kogia breviceps skull CT scan. Bottom: diagrams of ontogenetic stages of interparietal fusion in P. phocoena and K. breviceps

Evo-Devo Origins of the Toothed Whale (Odontocete) Skull Roof

In most mammals, the skull roof that covers and protects the brain is formed by two symmetrical bones: the parietals. But, in dolphins, a different, single bone forms the skull roof: the interparietal, which usually forms the back of the skull. How  did the interparietal get there?  Do other toothed whales and baleen whales have this anatomy too, or do they resemble other mammals? To answer these questions, we  examined fossils and fetuses from many different species. In contrast to prior assumptions, we found that the interparietal does not form the skull roof in all toothed whales but, in many baleen whales, it is found in the middle of the skull roof. And, it is not one bone, but  instead forms from three parts.

To learn more, click here.

3D renderings of CT scans of a deer skull and a dolphin skull. The left half of the skulls are cut away revealing sagittal views of the nasal passages and cranial vaults.

Building a Blowhole: Nasal Passage Reorientation in Prenatal Cetaceans

Early in embryonic development, cetacean (e.g., whale & dolphin) embryos resemble the embryos of other mammals, but by the time they are born, their noses have shifted position and orientation to become a blowhole. How does the nose end up in this new location? While all cetaceans have blowholes, members of of the two living cetacean sub-groups, toothed whales (odontocetes) and baleen whales (mysticetes) undergo different developmental transformations to turn their noses into blowholes. 

To learn more, click here.

First figure in Roston and Roth (2019) depicting telescoping of cetacean skulls.. A telescope, a color-coded dog skull, a color-coded dolphin skull, and a color-coded exploded dolphin skull showing wear the maxilla and frontal overlap

Telescoping of Cetacean Skulls & the Evolution of Craniofacial Sutures

Whales, dolphins, and porpoises (cetaceans) have some of the strangest skulls among mammals, in large part due to phenomena known as "telescoping"--extensive bone overlap and shortening of the distances between non-adjacent bones. Telescoping is an important example of the extremes of mammalian evolution and evolution of the role of craniofacial sutures in the skull. How did it evolve and how does it develop in living species? What function(s) might this unusual form provide in cetacean skulls?  And, what does this radical deviation from typical mammalian anatomy tell us about the "rules" of mammal skull evolution, development, and function?

To learn more about telescoping and cetacean skull evo-devo, click here. 

Prenatal Development of the 

Largest Species to Ever Live

In less than a year, blue whales grow from a single cell to a more than 21-foot-long newborn.  How do they transform from one cell into a fully functioning whale? With non-invasive imaging, we were able to see inside one of the smallest blue whale fetuses in scientific collections and learn more about how blue whales develop. 

To learn more, click here.