We also characterize the keratinized mouthparts of tadpoles as ectodermal appendages and propose that these novel vertebrate structures may have originated by partially co-opting the program that typically mediates development of mineralized teeth. More work is underway to explore this hypothesis!

4) We searched for vestigial dental development on the toothless frog mandible. We found no definitive evidence of tooth rudiments initiating in the lower jaw when teeth are forming on the upper jaw. Unexpected, because evolutionarily lost traits typically form at least partly during development.

3) We evaluated whether the tadpole jaw impacts developing teeth. Keratin may dictate the location of the earliest dental placodes, which are positioned far behind the tadpole "beak". Did keratin similarly displace teeth during the evolution of turtles, birds, & non-avian theropod dinosaurs?

2) We assessed if the genes underlying dental competence are conserved in the late-forming teeth of frogs. We found dental precursor expression patterns consistent with an odontogenic band, comparable to patterns observed in other vertebrates.

In this paper, we 1) describe the precise timing of tooth development in a typical anuran, the Cuban tree frog (Osteopilus septentrionalis). The earliest indication of tooth development is at the final stage of tadpole development (Gosner 40), coinciding with the larval keratinized mouthparts.

Our new paper is out in Royal Society Open Science! The metamorphic transition of the frog mouth: from tadpole keratinized mouthparts to adult teeth doi.org/10.1098/rsos...

"Carrot-tailed" chuckwalla (Sauromalus ater) basking in South Mountain Park, Phoenix

Ring-necked snake (Diadophis punctatus) displaying its unique defensive posture during fieldwork this weekend in Southern Indiana

Great outreach event today organized by @maggiehantak.bsky.social's UD Herpetology class at Dayton Metro Library! 100 folks stopped by to learn about Ohio amphibians & reptiles, importance of natural history collections, and more

We unexpectedly found similar expression patterns between tadpole keratinized mouthparts and true teeth, which may indicate that the origin of tadpole mouthparts in proto-frogs occurred via co-option of the tooth development program

Teeth are restricted to the upper jaw in all but one species, which inexplicably re-evolved mandibular teeth. We show the core regulatory network underlying odontogenic competence is conserved in the late-forming teeth of frogs but tooth development does not initiate in the edentate lower jaw.

Among vertebrates, frogs are unique in that they fail to develop teeth during embryonic development and instead form adult dentition during metamorphosis. Tadpoles evolved an alternative feeding apparatus composed of novel keratinized mouthparts.

Excited to share our new preprint, Tooth development in frogs: Implications for the re-evolution of lost mandibular teeth and the origin of a morphological innovation doi.org/10.1101/2025...

I'm recruiting a PhD student to join my lab at the University of Dayton (Fall 2025) to study the evo-devo of tadpoles! More info here: evol.mcmaster.ca/brian/evoldi...