what is the first one like?
A genus of extinct basilosaurid ancient whales.
Dorudon
Dorudon ("spear-tooth") is a genus of extinct basilosaurid ancient whales that lived alongside "Basilosaurus" 40.4 to 33.9 million years ago in the Eocene. 
what is baleen whale? A parvorder of the infraorder Cetacea. what is the lifespan of the latter mentioned? Over 200 years. what is the head like of these species? Elongated head how intelligent are they? Known to teach, learn, cooperate, scheme and grieve. what are some environmental hazards they are susceptible to? Plastic waste flotsam, damaged ozone layer, and ocean acidification. how does its respiration work? Deliberate breathers who must be awake to inhale and exhale. what are the threats it faces? Directly from drive hunting and indirectly from pollution. how does it die? UNANSWERABLE who are its ancestors? Dorudon of Dorudontidae.
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Dorudon [SEP] Introduction
Dorudon ("spear-tooth") is a genus of extinct basilosaurid ancient whales that lived alongside "Basilosaurus" 40.4 to 33.9 million years ago in the Eocene. They were about long and fed on small fish and mollusks. "Dorudon" lived in warm seas around the world. Fossils have been found along the former shorelines of the Tethys Sea in present-day Egypt and Pakistan, as well as in the United States, New Zealand, and Western Sahara.