Cambronatus

Content sourced from Wikipedia, licensed under CC BY-SA 3.0.

Cambronatus is a Devonian arthropod from Germany’s Hunsrück Slate. It is known from one species, Cambronatus brasseli, and measured about 7 cm long. It looked a lot like a modern shrimp.

The head carried a simple, shield-like plate. The first pair of head limbs were long biramous antennae with about 400 segments on the outer branch. The next four pairs were similar but made of many short joints with stout spines; these limbs appear to be uniramous. The fifth pair has clusters of smaller inward-facing spines. There were no eyes.

The body had 11 segments. The first ten segments carried limbs similar to the head but with a flap-like extension (an exopod). The eleventh segment was unusual: it had a tri-ramous limb with a flagellum-like first ramus and two paddle-shaped branches forming a tail fan along with the telson. The telson was fringed with spines and ended in a forked tip.

Cambronatus’s strange shape is why it seems almost Cambrian in its look. The species name honors Günther Brassel, who studied Hunsrück Slate fossils for many years. It likely lived in murky, low-visibility water, as suggested by the lack of eyes and numerous antennae. The head appendages were probably used to catch prey, while the trunk limbs provided most of the propulsion. The tail fan helped steer, with the flaps and possible drag-reducing adaptations making swimming more efficient. It probably swam just above the muddy bottom, detecting soft prey with its antennae and grabbing them with its head limbs.