CAIRO, Aug 10 (KUNA) -- A team of excavators from Mansoura University, Nile Delta, Egypt, documented a new discovery of fossils of the geographically widespread extinct family Basilosauridae which lived nearly 41 years ago.
The new basilosaurid genus and species, Tutcetus rayanensis, dating from the middle Eocene Epoch, were found in Faiyum Oasis, nearly 10 km. southwest Cairo, the University said in a statement on Thursday. This new whale is not only the smallest known basilosaurid, but it is also one of the oldest records of this family from Africa, the statement said, citing a research paper published by Communications Biology - an open access weekly journal from the London-based Nature Portfolio.
"Tutcetus allows us to further test hypotheses regarding basilosaurids' early success in the aquatic ecosystem, which lasted into the latest Eocene, and their ability to outcompete amphibious stem whales and opportunistically adapt to new niches after they completely severed their ties to the land," the paper says.
"Tutcetus also significantly expands the size range of the basilosaurids and reveals new details about their life histories, phylogeny, and paleobiogeography," it noted.
Soon after whales originated in the late early Eocene from small quadrupedal terrestrial artiodactyl ancestors in south Asia, semi-aquatic archaeocete whales rapidly dispersed westward to North Africa, West Africa, North America, and South America during the early middle Eocene.
As the late Eocene (Priabonian) progressed, the fully aquatic basilosaurid archaeocetes had replaced amphibious archaeocetes10 and were the most abundant whales and ultimately extended into the geographic ranges occupied by modern cetaceans.
Basilosauridae was the first family of archaeocete whales known to science, according to the paper. Basilosaurids were cosmopolitan, anatomically derived, and fully aquatic archaeocete whales that are thought to be close to the ancestry of extant (or crown) cetaceans. Basilosaurids are characterized by the loss of the maxillary third molar, modification of their forelimbs into flippers, a substantially reduced innominate which lacks any bony connection to the vertebral column, an increased number of posterior thoracic/lumbar vertebrae, and the development of paddle-like tails.
They range in size from around 4?m for Saghacetus osiris (Priabonian) to around 18?m for Basilosaurus cetoides (Bartonian to early Priabonian).
Basilosaurids are the best known archaeocetes of the African Paleogene. Not only were the vast majority of their fossil remains discovered in Egypt, but the most thoroughly documented basilosaurids, including the first fully aquatic cetaceans and early tail-powered swimming cetaceans, were discovered in Egypt's Faiyum Depression, which is home to the Wadi El-Hitan World Heritage Site, one of the world's most productive fossil whale sites. (end) mm.gb