Produced by the Population Genetics and Evolution class, Furman University

The Silurian: Anaspids
The Anaspida were a diverse class of jawless Silurian fishes. Anaspids were probably bottom feeders that siphoned small organisms off the bottom into their oral cavities (Virtual Fossil Museum 2010). Fossil records indicate that they were relatively small organisms, with a maximum length of 15 cm (White 2010). As true vertebrates fishes, Anaspids did have many characteristics of extant fish today; including gill slits and small protective scales on their outer layers. However, their backs were generally striped with a row of spikes for protection. Unlike ancestral ostracoderms that had a completely rigid bony helmet, anaspid heads were covered with large scales that are hypothesized to be made of bone deposits (Janvier 1997). The bony surface could have possibly protected their heads when dragging them across the ocean floor during feeding. The Anaspids are one group of diverse jawless fishes that are now only represented by the lampreys and hagfishes.

Page by Pete Calomiris
Anaspids. Picture From: Wikimedia Commons

Janvier P. 1997. Anaspida. The Tree of Life Project. Accessed February 2010.

White AT. 2003. Craniata: Hagfish, Lampreys and Anapsids. www.palaeos.com. Accessed February 2010.

The Virtual Fossil Museum. 2010. Silurian Anaspida Jawless Fossil Fish from Scotland. Accessed February 2010.