Paleozoic
Neoarchean
Bacteria-like unicellular creature, which is the ultimately unsuccessful result of a completely separate abiogenesis.
Bacterial colony which has convergently evolved a eukaryotic cell configuration. It forms a thick slab-like slick which crawls slowly around like a slime mould, feeding on cyanobacterial mats.
Paleoproterozoic
A multicellular creature that resembles the first animals, but is an earlier experiment with multicellularity that ultimately failed. Eukaryota.
Cryogenian
Sponge-like colonial animal which drifts in the oceans below the global ice sheet. It can affect its trajectory slightly as it filters the water actively. Porifera.
Ediacaran
Extremely early predator, a Spriggina-like animal that preys on smaller primitive animals. Bilateria.
Cambrian
Siphonophore-like colonial tunicate, which swims actively whilst filtering the water. Tunicata.
A Hallucigenia-like Onychophoran that has a profusion of spines. Hallucigeniidae.
A relative of Sidneyia that has a very wide body. Limulavida.
A larger relative of Yohoia that has much larger, trenchant raptorial appendages. Yohoiidae.
A relative of Myllokunmingia that has a very deep, fish-like body. Myllokunmingiidae.
Large predatory penis-worm, perhaps 2 feet long. Ottoiidae.
Giant predatory trilobite, 1 meter long. Dorypygidae.
Ordovician
An early jawless fish that has a covering of spiny scales. Arandaspididae.
Transitional gnathostome, whose jaws are still only partway developed from gill arches. Stem Gnathostomata.
Silurian
A relative of Euthycarcinus that has adapted to a partially terrestrial lifestyle. Euthycarcinida.
Partially terrestrial eyrypterid, which greatly resembles a giant spider, 60cm leg span. Stylonuridae novis.
Devonian
A descendant of Opabinia that survives as a relict in the Devonian. Opabiniidae.
Partially terrestrial placoderm, whose arm-like fore fins act as legs. Bothriolepididae.
Eel-shaped sarcopterygian. Osteolepidida.
Carboniferous
A relative of Holopterygius that is adapted to hover above the sea floor in order to snatch prey. Hadronectoridae.
A relative of Tullimonstrum that is adapted to hover over the substrate with rippling fins much like a cuttlefish. Chordata?
An Inopterygian that is a streamlined, open-ocean dweller. Iniopterygiformes.
Seed-eating early reptile, which actively climbs trees. Captorhinidae.
Primitive aquatic relative of flying insects, which uses its incipient wings to swim underwater. Ephemeroptera.
Permian
A relative of Zatrachys which has a backswept arrangement of cranial ornamentation. Zatrachydidae.
Aquatic pelycosaur whose adaptations are clear from its osteology. Ophiacodontidae.
Giant, conger-eel shaped anthracosaur anamniote. Embolomeri.
A relative of Edestus that has a single, upper-jaw tooth whorl that it uses like the rostrum of a sawfish, to stun or kill prey. Edestidae.
An ape-like arborial relative of Suminia, as heavy as a chimpanzee. Otsheridae.
A Gorgonopsian that has extremely long sabre canines, rivalling those of the sabre-toothed cats. Gorgonopsidae.
Gigantic, serpentine relative of Helicoprion, 20 meters long. Edestoidea.