Epoch: Late Cretaceous
Archelon for the most part was simply a huge sea turtle. At a whopping 4.5m long it was the largest sea turtle ever to swim. Despite its size though it fed on the usual turtle stuff, squids and jellyfish for example. One of the two significant differences between archelon and modern sea turtles is that its shell was not hard, rather of a leathery texture with a skeletal support system. This meant that whilst archelon was undoubtedly a huge animal, it was also the easiest to prey on for large predators. Because its size meant that firstly it was relatively slow compared to the giant mosasaurs that were patrolling the waters, and secondly, that it was very easy to spot. Whilst the shell was not as strong as a solid turtles shell, it would have definitely provided protection to some degree, so whilst it was an easy target it was not without hope. It also had another thing that it could use to its advantage, this was its powerful beak including a fair overbite which would have worked to slice through flesh will relative ease. This beak was something that archelon could have used as a defensive weapon if it had to, but one would assume that the large predators would not attack head on and therefore the main protection for the archelon was its shell. Therefore leaving this giant of the seas fairly vulnerable to attack. Regardless of this the genus was around for 10 million years so it must have been somewhat able to survive. Probably by using similar methods as sea turtles today, by laying huge numbers of eggs and having a survival rate of about 1 in 1000.
(via: Smithsonian Ocean Portal) (photo: Lexa Grutter)
What is the Biggest Shark? A Chart Shows the Diversity of Shark Sizes
Sharks come in all sizes. The largest is the whale shark, which has been known to get as large as 18 meters (60 feet). The smallest fits in your hand. Find out how these modern sharks stack up against the ancient Carcharodon megalodon. And if you’re a fan of great white sharks, you can download a shark-themed board game, track a shark named Omoo, and listen to a podcast about the species on our Great White Shark section.
(via: Smithsonian Ocean Portal)
(image: © Courtesy of the Aquarium of the Pacific, Long Beach, California)
Australian Giant Crab (Pseudocarcinus gigas) showing large claws, Tasmania, Australia by Fred Bavendam