Lecture 12 Flashcards
End-of-Cretaceous Paleogeography
Sea level was much higher during much of the Cretaceous. Low-lying
areas of Laurentia were covered by an epicontinental sea.
¡ The Western Interior Seaway divided the continent into two:
Laramidia to the west and Appalachia to the east.
¡ Sea level continued to fall and the seaway disappeared in the early Paleogene.
T-rex lived in the ______along the __________ of the Western Interior Seaway alongside many other dinosaurs,
crocodilians, turtles, and pterosaurs
….Forests along the Coatal Plains…
At the End-of-Cretaceous Terrestrial Ecosystem
Hell Creek Formation- T-rex fossils are found in the badlands of…
southern AB and SK,
but mostly found eroding out of the Hell Creek Fm of Mt, Wy
& the Dakotas.
T-rex is known from
50+ specimens with
good amounts of
preserved bones
(partial to almostcomplete skeletons) -See slide 6 for map of common fossil findings
What is the biggest T-rex?
Scotty replaced Sue as the
largest known fossil T-rex.
* Sue = 12.3 m long with a
hip height of nearly 4 m,
and weighing in close to
8.5 tonnes
* Scotty = 12.8 m long and
likely a few hundred kilograms heavier.
(Diametre and circumference of femur is used to estimate weight)
Sue
‘Sue’ is the most
complete specimen
ever found. Almost
90% of the skeletal
material is present.
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All that is missing are a few vertebrae, her left foot, some
gastralia & ribs, her right arm, and the claws on the left arm
We don’t know if Sue is male or female.
What is the oldest T-rex?
Sue and Scotty are amongst the oldest T-rex fossils
known, at about 28 years of age. This was probably
approaching an upper limit of about 30 years.
we determine
the age of a T-rex (or any
dinosaur for that matter) By counting the rings or LAGs
LAG = line of
arrested growth
Nanotyrannus ‘Jane’
Originally described and named as a small tyrannosaurid,
Nanotyrannus ‘Jane’ is now regarded to be juvenile T-rex.
Wyrex
Skin impressions
from the specimen
nicknamed ‘Wyrex’
reveals a pattern of
fine scales along
the sides of the
back, neck and tail.
No evidence of feathers
Can we tell if a T-rex is
male or female?
The answer is sometimes.
We don’t have any T-rex
fossils that were carrying
eggs, BUT there are two
T-rex specimens that have
been identified as female.
The first: ‘B-rex’
‘Dueling Dinosaurs’
An exciting discovery of a juvenile Tyrannosaurus rex and
Triceratops – prepared specimens to be revealed in April
2024 at the North Carolina Museum of Natural Sciences.
