Historic Fossils from the Mace Brown Museum

Today I visited the Mace Brown Museum. When you first walk in you are surrounded by historic creatures that have now been extinct for over millions of years. Armored fishes existed approximately 492-369 million years ago. There are two types of armored fishes, the ostracoderms and placoderms. Ostracoderms means “shelled-skin” and were found in early Devonian-age freshwater deposits in Europe. Placoderm means “plated skin” and were mostly found in freshwater deposits, but sometimes found in marine deposits. Placoderms had articulated armor plates that covered their head and thorax. 

The Dunkleosteus was the largest and fiercest of the placoderms. They reached lengths of 33 feet and weighed up to four tons. They were the top carnivores of their time. Dunkleosteus did not have teeth, instead they had two pairs of razor sharp bony plates, similar looking to a snapping turtle. The two gnathal plates sharpened themselves as they rubbed one another and grew continually so they never wore out. The bite force of the Dunkleosteus were estimated to be eight thousand pounds per square inch, which was the most powerful bite in the water until the rise of the megalodon shark.

The oldest fossil evidence of jawless fishes were preserved in early Cambrian rocks in China approximately 530 million years ago. Sharks appeared around 455 million years ago. Bony fishes first appeared in the fossil record around 420 million years ago during the Devonian period. Teleost fishes are a type of modern ray-finned fish. Through evolution Teleost fishes pectoral and pelvic fins have changed locations in today’s fishes. The pectoral fins are in front and the pelvic fins are below the center of mass which enhance their maneuverability.

The shark teeth that I found to be the most interesting is the Palaeocarcharodon Orientalis, or the extinct Pygmy White Shark, because the edge of these teeth are serrated, which most likely made it easier for them to chew up their food. They are 60 million years old and and were found at the Khowitca Plateau, Morocco.

The Megalodon was one of the largest marine apex predators ever to exist. Megalodon continued to grow bigger and bigger until reaching their maximum length prior to their extinction. A Megalodon jaws reached 6-7 feet in width and height when opened, big enough for a human to
walk into. A full grown Megalodon can reach lengths up to 65 feet. The bite force of the Megalodon puts the Dunkleosteus to shame. The bite force of the Megalodon ranged from 24 thousand to 41 thousand, which is even stronger than a T-Rex, and these sharks weighed up to 100 tons. Megalodons preferred to reproduce in warm, shallow, coastal waters because it was a safe environment for their young. This sort of environment had protection from predators and abundant food sources. As the shark aged, they migrated further offshore due to their large size. Their diet included whales and other large sharks and fish. They attack their prey similar to a great white shark, from below.

My favorite fossil is the Lepisosteus simplex, or the Gar pike, because I have caught a gar before and this fossil looks very similar to the one I have caught. It is crazy how similar the body style of this 50 million year old fossil and the modern day gar are.







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