Eight manatee bones (jaws, ribs, and other pieces) from the Pleistocene time period have been unearthed along the coast of Texas. The Pleistocene Epoch began approximately 2.6 million years ago and lasted until around 11,700 years ago – the most recent Ice Age also occurred during that time.
Manatees (also known as sea cows) are large marine mammals with flippers and a strong flat tail that can help them swim as fast as 15 mph (24 km/h) although their normal speed is around 5 mph (8 km/h). They grow between 8 and 13 feet long and weigh between 200 and 590 kilograms (440 to 1,300 pounds). They are herbivores that enjoy munching on sea grasses and algae among other vegetation.
While manatees are still around today and continue to spend their summers off the coasts of Texas and Florida before migrating to warmer waters down south during the winters, it appears as though their ancient Ice Age ancestors did the same.
Interestingly, seven of the eight bones belonged to the Trichechus manatus species which is the same type of manatee that travels to the Texas and Florida coasts to this day, while the other bone (a jaw bone) belonged to the extinct subspecies called Trichechus manatus bakerorum. (A picture of the jaw bone can be seen here.)
After extensive analysis, the bones revealed that the manatees frequently traveled to the Texas coast (and possibly even lived there permanently) between 240,000 and 11,000 years ago. The fact that the time period coincides with the Ice Age suggests that either the water along the Texas coast was still warm during that period, or that the manatees were able to adapt and live in colder water.
This surprised the researchers because they didn’t think that manatees would have been able to travel up to Texas because a major portion of North America and the Golf Coast were covered in glaciers and had very cold temperatures.
David Mohrig, who is a geologist from the University of Texas but wasn’t part of the research team, provided a plausible explanation that manatees from the Ice Age may have found inlets of water off the coast of Texas that stretched into the Gulf of Mexico that may have been a bit warmer.
In a statement, Sam Houston State University Natural History Collections curator William Godwin explained how they knew that the manatees were continuously visiting the coastal area of Texas, “We have them (bones) from one decade to another, so we know it's not from some old manatee that washed up, and we have them from different places,” adding, “All these lines of evidence support that manatee bones were coming up in a constant way.”
Their research was published in the journal Palaeontologia Electronica and can be read in full here.