
1) Transitional fossil
Found on
https://www.crosswordclues.com/clue/eusthenopteron

Eusthenopteron is a genus of prehistoric sarcopterygian (often called lobe-finned fishes) which has attained an iconic status from its close relationships to tetrapods. Early depictions of this animal show it emerging onto land, however paleontologists now widely agree that it was a strictly aquatic animal. The genus Eusthenopteron is known from s...
Found on
http://en.wikipedia.org/wiki/Eusthenopteron

genus of extinct lobe-finned fishes (crossopterygians) preserved as fossils in rocks of the late Devonian Period (about 370 million years ago). ... [1 related articles]
Found on
http://www.britannica.com/eb/a-z/e/54

(pronounced you-sthen-OP-ter-on) Eusthenopteron was a large, fleshy-finned bony fish that lived during the late Devonian (over 400 million years ago). Eusthenopteron had characteristics of early tetrapods, and may have been a forerunner of amphibians. Eusthenopteron had pyramidal bones in its paired fins, a structure similar to that of the limb bon...
Found on
http://www.enchantedlearning.com/subjects/dinosaurs/glossary/
No exact match found.