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Beck, Daniel D.

Department of Biology

Central Washington University

Ellensburg, Washington USA

Gienger, Chris M.

Center of Excellence for Field Biology

Austin Peay State University,

Clarksville, Tennessee USA

Davis, Jon

Rockwell Real Estate

Medford, Oregon USA

DeNardo, Dale F.

School of Life Sciences

Arizona State University

Tempe, Arizona USA

Emblidge, Patrick

Northwest Bat Hub

Oregon State University – Cascades

Bend, Oregon USA

Goode, Matt

University of Arizona

Tucson, Arizona USA

Holcomb, Kerry

U.S. Fish & Wildlife Service - Southern Nevada Office

Las Vegas, Nevada USA

Jones, Jason

Western EcoSystems Technology, Inc. (WEST)

Cheyenne, Wyoming USA

Nowak, Erika

Colorado Plateau Research Station

Northern Arizona University

Flagstaff, Arizona USA

Arguably, our paradigm of “lizard biology” has historically been biased toward more commonly studied

taxa, dominated by small, heliothermic species that are largely active on a daily basis. In this talk I’ll

explore how knowledge of helodermatid lizard (Monstersaur) biology can inform other realms of

herpetology, medicine, and conservation in ways that greatly enrich our answer to “What is a lizard?”

Heloderma first appeared in seasonal tropical environments over 23 mya, and later colonized the Sonoran,

Mojave, and Chihuahuan deserts of North America. Extant Monstersaurs span over 2000 miles and 22 o

latitude from the Mojave Desert in Utah to the tropical dry forests of eastern Guatemala. The substantial

molecular diversity of beaded lizards and their current geographic distribution align with the deep

evolutionary history of neotropical dry forests of Mexico and Central America. I’ll present a preliminary

summary of a large data set of body temperatures, assembled by Chris Gienger, a result of a collaboration

over decades among many Heloderma researchers. Our data from populations along a 1500-mile

latitudinal gradient, from the SW US to coastal Jalisco, show considerable variability in resting body

temperatures (from < 18 o C in Utah, to > 25 o C in Jalisco). Yet preferred activity temperatures are fairly

consistent throughout this latitudinal gradient, hovering around a mean of 30 o C for all populations. Use of

GLP-1 agonists (developed directly from the exendin-4 peptide discovered in Gila Monster venom) have

recently skyrocketed, powered by their promise as weight loss drugs. In 2023, the journal Science named

these mega blockbusters the breakthrough of the year, the GLP-1 agonist market topped $35 billion, and

Monstersaurs remain posterchildren for the value of biodiversity. So, what is a lizard? The answer is

complex, awe inspiring, and beautiful. But, like the bumpy lizards of the Helodermatidae, can’t really be

boxed into a simple definition.


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