May 28th, 2021
For today’s #FossilFriday feast your eyes on these beautiful lower jaws from the ceratopsian dinosaur, 𝑃𝑎𝑐ℎ𝑦𝑟ℎ𝑖𝑛𝑜𝑠𝑎𝑢𝑟𝑢𝑠 𝑙𝑎𝑘𝑢𝑠𝑡𝑎𝑖, recovered from the local Pipestone Creek Bonebed. The size and shape of these jaws are different because they are from different growth stages in the horned dinosaur’s life. The term used by palaeontologists mentioning the relationship of how bones transformed as animals aged is referred to as ontogeny.
The way these lower jaw bones (dentaries) are arranged, represents a very general idea on the bone development of the extinct animal, from youngest at the top to most mature at the bottom. These lower jaw bones have slots or sockets where teeth use to be housed. The teeth have fallen out from their original sockets. This likely happened after the animals died, during stages of decomposition.