April 9th, 2021

Here is the right maxilla or upper jaw bone of β€œJane” (BMRP 2002.4.1), a ~13-year-old π‘‡π‘¦π‘Ÿπ‘Žπ‘›π‘›π‘œπ‘ π‘Žπ‘’π‘Ÿπ‘’π‘ . Jane was found in the Hell Creek Formation of southern Montana back in 2001 by a field crew from the Burpee Museum of Natural History.

Jane fills a critical gap in our knowledge of π‘‡π‘¦π‘Ÿπ‘Žπ‘›π‘›π‘œπ‘ π‘Žπ‘’π‘Ÿπ‘’π‘  ontogeny – the growth stages animals go through as they age. After the skeleton’s initial discovery, scientists analyzed the growth rings in Jane’s leg bones. Using histological methods, it was determined this tyrannosaur was only 13 years old and had not yet reached adulthood. Contrary to earlier claims of Jane being a different species of tyrannosaur, this specimen is indeed a π‘‡π‘¦π‘Ÿπ‘Žπ‘›π‘›π‘œπ‘ π‘Žπ‘’π‘Ÿπ‘’π‘  π‘Ÿπ‘’π‘₯, just not a fully developed one.

This #FossilFriday is brought to you by Dr. Thomas Holtz, this week’s guest on the museum’s Virtual Speaker Series. His talk will be live streaming on the museum’s YouTube channel tomorrow at 3:00 PM!

Right maxilla of Jane the subadult π‘‡π‘¦π‘Ÿπ‘Žπ‘›π‘›π‘œπ‘ π‘Žπ‘’π‘Ÿπ‘’π‘  π‘Ÿπ‘’π‘₯. Photo courtesy of Dr. Thomas Holtz.
Skeletal mount of Jane at the Burpee Museum of Natural History. Photo credit: Zissoudisctrucker, CC BY-SA 4.0 , via Wikimedia Commons.
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