04Paleozoic
Trilobites
Trilobita
They occupied seafloors for nearly 300 million years, and their compound eyes preserve secrets of early vision.
EXTINCT ATLAS WIKIEXTINCT LIFE ARCHIVEBack to archivePeriod · 486.85–443.1 million years ago
Ordovician Animals & Marine Life
Discover Ordovician seas through cephalopods, trilobites, early fishes and the communities that followed the Cambrian.
Life and the fossil record
Marine animals occupied increasingly varied ecological roles. Shelled seafloor communities and swimming predators illuminate different food webs. Glaciation and environmental disruption near the period’s end caused major losses, but surviving lineages continued into the Silurian.
34Paleozoic
Cameroceras
Cameroceras trentonense
A long straight shell housed one of the largest predators of Ordovician seas.
167Paleozoic
Sacabambaspis
Sacabambaspis janvieri
A broad head shield enclosed its front half, with forward-set eyes and a flexible tail behind the armored box.
207Paleozoic
Endoceras
Endoceras giganteum
A straight conical shell several meters long made it one of the most conspicuous large cephalopods of Ordovician seas.
208Paleozoic
Arandaspis
Arandaspis prionotolepis
It lacked jaws and paired fins, but its head and gill region were enclosed within strong armor.
255Paleozoic
Giant Isotelus
Isotelus rex
At nearly seventy centimeters, it is among the largest complete trilobites ever found.
306Paleozoic
Tortotubus
Tortotubus protuberans
Branching microscopic hyphae show fungi helping to build the earliest soils.
310Paleozoic
Chain coral
Halysites catenularius
Linked tubes formed honeycomb chains across Paleozoic reefs.
311Paleozoic
Atrypa
Atrypa reticularis
Fine radial ribs covered rounded shells that once crowded ancient seabeds.
415Paleozoic
Receptaculites
Receptaculites oweni
Spiraled diamond plates formed a calcified pinecone-like body.
416Paleozoic
Cyclocrinites
Cyclocrinites dactioloides
Whorled calcified branches surrounded a central axis like an underwater bottlebrush.
429Paleozoic
Aegirocassis
Aegirocassis benmoulai
A two-meter filter-feeding radiodont was an early analogue of giant plankton feeders.