Research

Broadly, my research focuses on growth and development and how these processes influence the evolution of vertebrates. Development is a universal feature of biology, and understanding the history of development is a major part of understanding the evolution of life.

To explore this biological process I investigate patterns of pre- and postnatal change during ontogeny, mostly in archosaurian reptiles. This group exploded in diversity and disparity in an evolutionary radiation following the largest mass extinction in earth history, marking the origin of groups that are still major ecological players today. Therefore, this group is an excellent study system to understand the tempo and mode by which new body forms evolve and the rise of new clades to ecological dominance

I use my interdisciplinary background to explore biological questions in a deep-time context:

Photo by Z. Murphy

How can new technologies be used to answer questions regarding the evolution of vertebrates?

 

Although some paleontological field techniques have remained the same for roughly a century, the influence of new technologies has rapidly changed the way this discipline is practiced. I am interested in using these new technologies to answer questions regarding vertebrate evolution. Whether it is Google Earth to find new fossil localities, Computed Tomography (CT) technology to explore and describe previously unobservable anatomical features, three-dimensional surface scans to digitize and share unique fossils with scientists around the world, or novel imaging techniques to study embryos at resolutions and developmental stages previously unavailable, I am active in integrating cutting-edge technology in answering major evolutionary questions

How can the ontogenetic age/skeletal maturity of fossil vertebrates be determined?

 

Determining the ontogenetic status of a fossil individual is crucial to correct identification and proper systematic placement. Ontogenetically immature individuals may be misidentified as adults of different taxa, which can complicate phylogenetic reconstruction, paleodiversity estimates, and paleobiogeography. It is therefore crucial to understand ontogenetic patterns (both histological and morphological), especially those that are phylogenetically conserved. Although size has usually been taken as a proxy for developmental maturity, skeletal maturity, body size, and ontogenetic age can be disjunctive, and I am interested in ways to account for this complication in determining relative maturity in fossil vertebrates.

Art by A. Atuchin

In what ways can the ontogeny of extinct organisms inform us of their biology?

Ontogenetic information, particularly osteohistology, is commonly used to form hypotheses about the paleobiology of extinct organisms, including metabolism, growth rate, ecology, and population structure. This area of research has generally focused on the transition from non-avian to avian dinosaurs and non-mammalian to mammalian synapsids. I am particularly interested in analysis of growth patterns surrounding the origin and early evolution of dinosaurs during a transition from rare and small-bodied taxa to the dominant vertebrate life on land

How do conserved developmental patterns influence evolution?

 

Comparative ontogenetic studies are necessary to determine the tempo and mode of the evolution of development, and ontogenetic series of fossil organisms allow this study to be undertaken in the context of geological time. To explore this question, I integrate embryology with the fossil record to determine how developmental strategies are conserved through the evolutionary history of vertebrates and how developmental pathways influence the evolution of morphology. Untangling the relationship between development and evolution of form, and the relative timing of ancestral and derived features appearing during ontogeny, has been a grand challenge in biology for over 150 years, and my work fits into this broader story

What influences the rise of major vertebrate groups?

 

Diversity, disparity, and ecological importance are not distributed evenly among groups—instead, some clades take over the planet, whereas others remain low in species richness, limited in geographic range, and constrained in the number of ecological niches they exploit. I am interested in how clades rise to ecological dominance, focusing on both intrinsic factors (e.g., growth strategies, morphological novelty), extrinsic factors (e.g., climate and biogeography, niche-clearing via mass extinction events), and timing (e.g., rapid vs. gradual rises and falls in dominance). To explore these questions, I focus on two major transitions—the 'original' rise of dinosaurs from minor players to the dominant vertebrate group on land, and the 'second' rise of dinosaurs that occurred with the origin and diversification of birds, which is the most speciose vertebrate clade alive today

© 2019 Christopher Griffin

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