Juvenile T. rex are different from Small Tyrannosaur

Summary

A recent reanalysis of fossils initially considered juvenile T. rex specimens reveals a distinct species, Nanotyrannus lancensis. Contrary to previous interpretations, these fossils represent adults of a smaller tyrannosaur with distinctive features such as narrower jaws, longer legs, and larger arms than the iconic T. rex. Originally named decades ago, Nanotyrannus had been misidentified as a young T. rex, and this study sheds light on its true identity as a smaller, long-armed relative with a distinct snout structure.

Re-examining Fossils and Challenging T. rex Relationship

Palaeontologists, Dr. Nick Longrich and Dr. Evan Saitta conducted a thorough re-analysis of the Nanotyrannus skull discovered in Montana in 1942—the debate over whether Nanotyrannus is a distinct species or a juvenile T. rex has persisted for decades. By examining growth rings, Nanotyrannus anatomy, and a newly identified young T. rex fossil, the researchers aim to clarify the relationship between these two dinosaur species.

Nanotyrannus Growth Patterns: Insights from Bone Rings

Researchers studying Nanotyrannus bones discovered a unique growth pattern by examining the density of growth rings. The analysis indicated that as the rings approached the outer layer of the bone, their proximity increased, suggesting a slowing growth rate. This finding challenges the previous assumption that these dinosaurs were fast-growing juveniles, indicating that they were likely nearing full size.

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Nanotyrannus’ Growth Secrets

By closely examining growth rings in Nanotyrannus bones, researchers found evidence suggesting that these dinosaurs were approaching full size, contrary to the belief that they were rapidly growing juveniles. The growth rings’ increased density toward the outer layers of the bone indicated a slowing growth rate. Modelling the fossils’ growth revealed an estimated maximum size of around 900-1500 kilograms and five meters, providing valuable insights into the growth patterns of these creatures compared to their larger relative, the T. rex.

Nanotyrannus and T. Rex Fossil Study

Study supporting the distinct nature of Nanotyrannus and T. Rex species reveals a lack of evidence for transitional fossils displaying features of both, challenging the notion of one evolving into the other. Rigorous examination of various fossils indicates clear identification as either Nanotyrannus or T. Rex, debunking the hypothesis of a direct evolutionary link. Furthermore, growth patterns in other tyrannosaurs do not align with the idea that these specimens represent young T. Rex, reinforcing the understanding of separate species within the tyrannosaur family.

Tyrannosaur Mystery: Nanotyrannus and the Absence of Young T. rex

Dr. Longrich’s research challenges the conventional belief that Nanotyrannus is a juvenile Tyrannosaurus rex (T. rex). By comparing features of juvenile tyrannosaurs, the study suggests that Nanotyrannus exhibits distinctive characteristics, indicating it may be a separate species. The absence of evidence for young T. rex individuals adds an intriguing layer to the mystery, prompting questions about the growth patterns and unique development of Nanotyrannus in the tyrannosaur family.

Unearthing Rare Evidence of Young Tyrannosaurus Rex

Palaeontologists led by Dr Nicholas Longrich have made a significant discovery challenging previous notions about the existence of young Tyrannosaurus rex (T. rex). The researchers identified a juvenile T. rex skull bone, specifically the frontal bone, with distinct features that differentiate it from Nanotyrannus, another dinosaur species. The rare find, housed in a San Francisco museum, provides valuable insight into the early stages of these iconic predators, with the skull measuring about 45 cm long and the entire body estimated at around 5 meters. This discovery challenges the belief that juvenile T. rex specimens are absent, emphasizing their scarcity rather than their non-existence.

Nanotyrannus Features

Researchers have presented compelling evidence supporting the idea that Nanotyrannus is a distinct species, diverging significantly from its well-known relative, Tyrannosaurus rex. The newly studied dinosaur exhibited a more slender build, longer limbs, and notably larger arms, challenging the stereotypical image of T. rex with its famously short limbs. This revelation sheds light on a unique dinosaur species that was smaller, faster, and more agile than its robust counterpart.

Nanotyrannus are distinct from T. rex

The study challenges the conventional understanding of Nanotyrannus, proposing that this dinosaur, characterized by long arms and distinct features, may not belong to the Tyrannosauridae family, unlike its well-known relative, T. rex. The findings add a layer of complexity to the ongoing debate in palaeontology and suggest that Nanotyrannus relied on speed rather than size and strength, setting it apart from its iconic cousin.

Controversy in Paleontology: Reassessing Nanotyrannus

Nanotyrannus has long been a subject of contention within palaeontology, with initial assumptions considering it a juvenile T. rex. However, the recent study, led by researchers like Longrich, challenges this perspective, highlighting the need for a reevaluation of Nanotyrannus as a distinct predator with its evolutionary lineage.

Journal Link: https://www.mdpi.com/2813-6284/2/1/1