_NATURE ENVIRONMENT ichthyology

_Common Core

An excavated Belgian quarry provides some of the earliest evidence of schools of different fish species using a common nursery to raise their young.

_Ted Daeschler

Daeschler is an associate professor in the BEES department and associate curator and chair of vertebrate zoology at the Academy of Natural Sciences. His current research program in vertebrate paleontology focuses on the vertebrate fauna of the Late Devonian Period in eastern North America.

A team of scientists uncovered a rare fossil site believed to be among the earliest evidence of different fish species using the same nursery.

A quarry in Strud, Belgium, excavated between 2004 and 2015 by French and Belgian scientists, was home to multiple species of placoderms, which are extinct, armored fish that represent some of the earliest jawed vertebrates on Earth. The site yielded smaller-sized fossils showing that immature placoderms occupied the area in the Devonian period, an era predating the dinosaurs by hundreds of millions of years. No mature fish were found, indicating that the fossils were part of a nursery, according to a study published in PLOS One.

The abundance of juveniles from three different types of placoderm fossils — Grossilepis rikiki, Turrisaspis strudensis and Phyllolepis undulata — opens questions for scientists like Ted Daeschler, an associate professor in the College of Arts and Sciences and associate curator of vertebrate zoology at the Academy of Natural Sciences of Drexel University. Daeschler co-authored the paper with Sébastien Olive, then a post-doctoral fellow at the Academy.

Fishing_hole

An artist’s depiction of how fish used the Strud nursery ecosystem, including the three different placoderm species discovered at the site.

“This is the first time that it can be demonstrated that several species seem to have used a common nursery,” Daeschler says. “It makes us wonder: Has that been a common reproductive strategy through time?”

Ultimately, Olive and Daeschler hope the Strud site provides a lens through which scientists can study current conditions.

“Geologists say that the present is the key to understanding the past. But we can also say that the past is the key to understanding the future,” Olive says.