It grew more than five meters long and weighed up to three tonnes. They are thought to have been placid browsers, although it has been suggested that they also eat insects. They were among the last dinosaur groups to evolve. Paracyclas Occurring in Devonian rocks in North America, Europe and Australia, Paracyclas is an early member of a group of clams known as Lucinacea. Living members of the group are borrowers.
Water containing food and oxygen is pumped through the tube in to the shell.
It is expelled out the back through a siphon that also extends to the surface. Paracyclas probably functioned in a similar way. A crinoid with a small, bullet shaped head, Paradichocrinus also was distinguished by branching arms. See also Crinoids Paradoxides Known from Europe, North America and northern Africa, Paradoxides was a Middle Cambrian trilobite. It was a primitive form, with a very small tail.