John Michalski, “A Review of the Fossil Record of Latex”
Mentor: Victoria McCoy, Geosciences
Oral Presentation Block 2

When humans think about latex, we typically associate it with gloves, mattresses, and practically all rubber products. But in the natural world, latex is produced by plants and serves as a chemical defense against herbivorous insects. Poisonous and in some plants very sticky, latex is released from laticifers in response to a feeding insect to minimize further damage and seal a newly inflicted “wound.” The latex can either deter the insect through its taste/toxicity or trap it to the plant. Latex is thought to have independently originated in various plant families across the world, and further developed its chemical complexity through coevolution with herbivorous insects. But while our pool of study for latex is abundant in the modern era, reports of prehistoric latex are much rarer, hampering our understanding of latex evolution. This literature review examines all reported occurrences of fossil lates, to assess its stratigraphic and geographic distribution. Based on the results of this review, latex first appears at the terminal stage of the late Cretaceous, just before the K-Pg mass extinction. By the Eocene, fossil latex is reported much more commonly in the literature and is known from multiple families across multiple continents, and throughout the Cenozoic the record continues to expand. I anticipate that more reports of fossil latex will be added to this record in the coming future as more material for fossil latex is discovered or studied. For now, it would appear that latex was a relatively recent adaptation among plants, and it became more and more common as modern plants diversified and expanded.