Research Highlights: Massive New Species from Cambrian Period Discovered in Canada
- Radiodonts are arthropods that existed worldwide during the Cambrian period.
- Radiodonts are known by their distinctive frontal appendages which are structurally diverse and used for many functions.
- Radiodonts were among the largest and most diversified lower palaeozoic predators.
- Lower Palaeozoic includes three geological systems: the Cambrian (541.0 to 485.4 million years ago), the Ordovician (485.4 to 443.4 million years ago) and the Silurian (443.4 – 419.2 million years ago).
- These animals were widely distributed around the world occupying different ecological niches including benthic foragers, nektonic suspension feeders, and apex predators.
- Benthic foragers search for relatively sessile prey usually at the lowest level of a body of water, while suspension feeders feed on particles of organic matter suspended in the water.
- Researchers discovered the largest Cambrian hurdiid radiodont known so far.
- Hurdiidae are known to have frontal appendages with distal region composed of 5 subequal blade-like endites, alongside the enlarged head carapaces and tetraradial mouthpart.
- Endite is one of the appendages of the inner side of the limb of an arthropod.
- Researchers named the newly discovered species as Titanokorys gainesi, gen. et sp. nov.
- The new species was discovered at Burgess Shale.
- Burgess Shale is a fossil-bearing deposit exposed in the Canadian Rockies of British Columbia in Canada and it is popular for the exceptional preservation of the soft parts of its fossils.
- Researchers speculated that the new species can reach half a meter in length.
- The new species has a very large egg-shaped central carapace with distinct short posterolateral projections and a frontal spine.
- Analyses emphasize the high diversity of carapace structures in hurdiids.
- Results suggest that Titanokorys bridges a morphological gap between forms with short and long carapaces.
- However, carapace shape is prone to homoplasy and shows no consistent relationship with trophic ecology.
- Homoplasy is the similarity in form or function between parts of different species that are not attributable to their common ancestor but is the result of parallel or convergent evolution.
- Trophic ecology is the study of the structure of feeding relationships among organisms in an ecosystem.
- Titanokorys shares similar rake-like appendages for sediment-sifting with Cambroraster.
- Cambroraster is characterized by a significantly enlarged horseshoe-shaped dorsal carapace.
- The occurrence of Titanokorys and Cambroraster on the same bedding planes emphasizes potential competition for benthic resources and the high diversity of large predators supported by Cambrian communities.
Caron J.-B. and Moysiuk J. 2021. A giant nektobenthic radiodont from the Burgess Shale and the significance of hurdiid carapace diversity. R. Soc. open sci.8210664210664. http://doi.org/10.1098/rsos.210664