Graptoloidea - Graptolites were minute individual tube-shaped animals ... In life, the rhabadosome was suspended from a "float" by a slender thread called a nema. Late Ordovician Period - The ...

like graptolites, that no longer exist. The extinction event, known as the end-Ordovician, was one of the five biggest of the past half billion years. It coincided with extreme changes in climate ...

Learn more about the time period that took place 488 to 443 million years ago. 3 min read During the Ordovician period, part of the Paleozoic era, a rich variety of marine life flourished in the ...

Skevington (1978) suggests that Ordovician graptolites may have shunned cold-water areas. The scarcity of such fossils in the Meguma may be a consequence of a near-polar setting.