Fossil research reveals the oldest evolutionary ‘arms race’

A study led by researchers at the American Museum of Natural History provides the oldest known example in the fossil record of an evolutionary arms race. These predator-prey interactions, between small shelled animals distantly related to brachiopods and unknown marine animals capable of penetrating their shells, led to the development of modern-day South Australia. It happened in the ocean that covers it.

The study, published in the journal Current Biology, provides the first demonstrable record of an evolutionary arms race during the Cambrian.

“Predator-prey interactions are often touted as a major factor in the Cambrian explosion, especially with regard to the rapid increase in the diversity and abundance of biomineralizing organisms during this period. However, there is a lack of empirical evidence that shows direct prey responses, from predator to predator, and vice versa,” said Dr. Kremlin, a postdoctoral researcher in the museum’s Department of Paleontology and lead author of the study. said author Russell Bicknell.

An evolutionary arms race is a process in which predators and prey continually adapt and evolve in response to each other. This dynamic is often described as an arms race, as improvements in the capabilities of one species lead to corresponding improvements in the capabilities of other species.

Bicknell and his colleagues at the University of New England and Macquarie University in Australia studied a large sample of fossilized shells of Lapworthella fascita, an early Cambrian species of arachnid, collected in South Australia.

More than 200 of these very small specimens, which vary in size from slightly larger than a grain of sand to slightly smaller than an apple seed, contain burrowing predators (possibly a type of mollusc). There is a hole drilled by (high). Or worms.

The researchers analyzed these specimens in relation to geological time and found that shell wall thickness increased over a short period of time, coinciding with an increase in the number of perforated shells. This is a microevolutionary arms race in which L. fasciata finds ways to strengthen its carapace against predation, and predators invest in the ability to pierce their prey even as their armor grows larger and larger. It suggests that.

“This highly important evolutionary record demonstrates for the first time that predation played a pivotal role in the proliferation of early animal ecosystems, and that such phenotypic changes occurred rapidly during the Cambrian explosion. “It shows what happened,” Professor Bicknell said.