Dueling Dinosaurs: Fossil Challenges T. rex Ideas
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Nanotyrannus Confirmed as Distinct Species: Dueling Dinosaurs Fossil Resolves Debate
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The Dueling Dinosaurs and the Nanotyrannus Debate
A complete tyrannosaur skeleton has just ended one of paleontology’s longest-running debates-whether Nanotyrannus is a distinct species, or just a teenage version of Tyrannosaurus rex.
The fossil, part of the legendary “Dueling Dinosaurs” specimen unearthed in Montana, contains two dinosaurs locked in prehistoric combat: a Triceratops and a small-bodied tyrannosaur.
That tyrannosaur is now confirmed to be a fully grown Nanotyrannus lanceensis-not a teenage T. rex as many scientists once believed.
Key Findings and Evidence
“This fossil doesn’t just settle the debate. It flips decades of T.rex research on its head,” says Lindsay Zanno, associate research professor at North Carolina State University, head of paleontology at the North Carolina Museum of Natural sciences, and coauthor of the study in Nature.
Using growth rings, spinal fusion data, and developmental anatomy, the researchers demonstrated that the specimen was around 20 years old and physically mature when it died. Its skeletal features-including larger forelimbs, more teeth, fewer tail vertebrae, and distinct skull nerve patterns-are features fixed early in development and biologically incompatible with a juvenile T. rex.
Growth Rings and Skeletal Maturity
Analysis of the bone growth rings revealed that the Nanotyrannus specimen had completed its growth, indicating it was not still developing like a juvenile T. rex would be. The presence of fused vertebrae further supports the conclusion of skeletal maturity.
Distinct Anatomical Features
Several key anatomical differences distinguish Nanotyrannus from T. rex,even accounting for age.These include:
- Forelimb Size: Nanotyrannus possessed proportionally larger forelimbs than T. rex.
- Tooth Count: The specimen had a higher number of teeth than typically found in T. rex.
- Tail Vertebrae: Nanotyrannus had fewer tail vertebrae.
- skull nerve patterns: Distinct patterns in the skull suggest differences in sensory capabilities.