Basilosaurid Whale

Possible Identification: Chrysocetus (golden whale)

Geologic Era: Eocene

Location Found: Morocco

Size: Unknown (5-6 meters long based on Dorudon)

Estimated Range: Modern oceans between Americas and North Africa

Extinction: 37.8 million years ago

Below are two views of a thoracic or lumbar vertebra of a basilosaurid/dorudontid whale. The processes are mostly gone, though the centrum is mostly intact. Evidence of the cartilage discs between vertebrae is seen by the roughened surface on the second photo. This bone still has some remnants of sandstone matrix clinging to it.

Vertebrae like these are frequently sold as “basilosaurus” vertebrae. This is not the case. The only places where Basilosaurus itself is found is in the American Southeast, Egypt, and Pakistan. The ones coming out of Morocco are basilosaurid whales, specifically durodontid. They are related, but not the same thing. Dorudontid whales are much smaller than Basilosaurus, and could have easily been their prey. Several durodontid whales have been recorded from the Dakhla sediments, so my identification as Chrysocetus is a best guess.

Many of the durodontid whales were of similar size (in the 5-6 meter range) and so would have been mid-level predators in their ecosystems. Potential prey might have included fish and smaller whales. Animals like Chrysocetus would have themselves been potential prey for large sharks like C. augustidens or Basilosaurus, its larger cousin. Durodontid whale bones do occasionally show feeding marks that match Basilosaurus, so whale-on-whale predation certainly did happen, though to what extent is not exactly certain.

Image Credits:

Life Restoration (Dorudon): By Nobu Tamura – Own work, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=19461116

Cynthiacetus Skeleton: By Shadowgate from Novara, ITALY – Museum of Natural History, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=36457109