January's Fossil of the Month - Conocoryphe (Conocoryphe spp.)
Family: Conocoryhphe Family (Conocoryphidae)
Time Period: 505 Million Years Ago (Mid Cambrian)
First appearing alongside most living animal phyla during the Cambrian Explosion roughly 538 million years ago and persisting until around 251 million years ago when they were driven to extinction in the most extreme extinction event in the earth's history, the Great Dying, the Trilobites were a large, diverse and extremely successful group of marine arthropods characterised by their thick exoskeletons which were divided into three major sections known as lobes (earning them their name, which translates roughly to "three lobes.") Throughout their over 270 million years on earth trilobites diversified massively as different species adapted to exploit different habitats and ecological niches; while many early trilobites were seafloor-dwelling detritivores, later species such as Hypodicranotus striatulus, show adaptations for swimming freely, while Cruziana (known only from its fossilized footprints) seemed to plough the sediment beneath it to filter out organic material, and members of the genus Olenoides exhibit head anatomy that suggests that they may have been active predators that fed on smaller invertebrates. Compared to later oddballs such as the stalk-eyed Asaphus kowalewskii or extremely spiny Dicranurus monstrous the members of the genus Conocoryphe, an early trilobite genus found commonly in Cambrian-aged rock deposits from North Amerca and western Europe, appear generic except for one unusual characteristic; most species in this genus lack the large compound eyes of most trilobites entirely, suggesting that as bottom-dwellers with limited access to sunlight they had no need for sight and relied on alternative senses to navigate and find food. As if the loss of eyesight in such early animals wasn't unusual enough, a single later Conocoryphe species, Conocoryphe oculata, possessed grooves on its head that suggests that members of this species regained the eyes their ancestors had lost (possibly indicating that they lived in shallower, better-lit waters than their relatives.)
---------------------------------------------------
Image Source: Here
