American Oceans

New Species of Extinct Whale Discovered

A team of international scientists led by Egyptian researchers has made a significant discovery: a new species of extinct whale named Tutcetus rayanensis that inhabited the ancient sea covering present-day Egypt around 41 million years ago.

a close up of Tutcetus Rayanensis in a 3d illustration

This whale is the smallest known basilosaurid and is among the earliest members of its family in Africa.

Despite its small size, Tutcetus provides valuable insights into the life history, phylogeny, and paleobiogeography of early whales.

Basilosauridae and Whale Evolution

a rendering of a basilosaurid whale

Basilosauridae is a group of extinct fully aquatic whales that represents a crucial stage in whale evolution as these creatures transitioned from land to sea.

They evolved fish-like characteristics such as a streamlined body, strong tail, flippers, and tail fin.

They also retained the last visible hind limbs, which resembled “legs” but were likely not used for walking and may have been involved in mating instead.

Tutcetus Rayanensis: An Insight into Early Whale Evolution

a rendering of Tutcetus Rayanensis basilosaurus

The newly discovered Tutcetus rayanensis, found in middle Eocene rocks, sheds light on early whale evolution in Africa.

The genus name, Tutcetus, is inspired by the famous Egyptian Pharaoh Tutankhamun, signifying the specimen’s small size and subadult status.

The species name, rayanensis, refers to the Wadi El-Rayan Protected Area in Fayum, where the holotype was discovered.

Tutcetus rayanensis is considered a vital step in understanding the transition to a fully aquatic lifestyle in the evolutionary journey of whales.

The holotype specimen includes a skull, jaws, hyoid bone, and atlas vertebra of a small-sized subadult basilosaurid whale embedded in a compacted limestone block.

With a length of about 2.5 meters and a body mass of approximately 187 kilograms, Tutcetus is the smallest known basilosaurid to date.

Significance of the Discovery

a whale fossil in rock

The discovery of Tutcetus rayanensis has broad implications for our understanding of the size range, life history, and paleobiogeography of basilosaurid whales.

Detailed analyses of the species’ teeth and bones using CT scanning enabled the researchers to reconstruct its growth and development pattern, providing unparalleled understanding of early whale life history.

The rapid dental development and small size of Tutcetus suggest a precocial lifestyle with a fast pace of life history for early whales.

Furthermore, the discovery contributes to our comprehension of the basilosaurids’ success in the aquatic environment, their capacity to outcompete amphibious stem whales, and their adaptive ability to new niches after severing ties to the land.

This transition likely occurred in the (sub)tropics.

The find also has significant paleobiogeographic implications, indicating that basilosaurids likely achieved rapid spread over the Southern Hemisphere, reaching high latitudes by the middle Eocene.

The ancient sea in present-day Egypt might have been a crucial breeding area for ancient whales, attracting them from various locations and drawing larger predatory whales like Basilosaurus to the region.

Add comment