First T. rex Hatchlings Identified from Neglected Museum Fossils

Paleontologists led by Nick Longrich of the University of Bath examined isolated bones that had been stored in museum drawers for decades. Among the fragments, a tiny third metatarsal and several teeth were recognized as belonging to a very small Tyrannosaurus rex, representing the first confirmed hatchling specimens of the iconic predator. The find was published in the journal *Biology* (2026).

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Longrich noted that the scientific community has traditionally favored large, complete skeletons, leaving minute, isolated bones under-studied. This bias meant that hatchling material remained “stuck in a museum and neglected,” despite its potential to reshape understanding of dinosaur development.

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Measurements indicate the principal hatchling was about 75 cm (30 in) long and weighed roughly 2.5 kg (5.5 lb), with an estimated hatch-mass of 1.7 kg—significantly smaller than earlier conjectures of a one-meter length at birth. From these dimensions, researchers inferred that T. rex eggs were modest in size, and that a single clutch likely contained 20–30 eggs. Such a strategy aligns more with an r-strategist reproductive model (many offspring, low individual investment) rather than the K-strategist model previously assumed for large theropods.

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Longrich and his team emphasized that the porous bone surface and vascular network confirm the specimens’ immaturity. Co-author Eric Snively highlighted the surprising similarity of hatchling teeth and foot bones to those of adult T. rex, suggesting early functional capabilities. The authors propose that tyrannosaur parental care occupied an intermediate evolutionary position between crocodilian-type minimal care and the intensive nurturing seen in modern birds.

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• “Going through museum collections, my colleagues and I have discovered the first remains of hatchling tyrannosaurs,” — Nick Longrich, paleontologist, University of Bath

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• “Paleontologists overlook these little remains, which are almost always isolated bones, in favor of larger and more complete skulls and skeletons,” — Nick Longrich

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• “The surface of the bone was incredibly porous,” — Nick Longrich

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• “This is the foot bone of a very, very tiny T. rex. This is the smallest T. rex that we've ever seen,” — Nick Longrich

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• “I was most surprised by how closely the hatchling Tyrannosaurus fossils resembled those of big adults,” — Eric Snively, paleontologist, Oklahoma State University

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• “It shows tyrannosaurs are transitional between reptiles like crocodilians and turtles on the one hand, and modern birds on the other,” — Nick Longrich

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