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T. Rex Grew Up Slower, Reaching Full Size at 35–40, PeerJ Study Finds

Polarized-light microscopy of tyrannosaur leg bones uncovered hidden growth rings that overturn earlier age estimates.

Overview

  • Researchers analyzed 17 specimens, largely from Montana and North Dakota museum collections, to construct a revised growth curve.
  • The team used thin-section histology, four ring-counting methods, and statistical modeling to address closely spaced growth marks.
  • Findings indicate a rapid adolescent growth spurt from roughly ages 14 to 29, with yearly gains of about 800 to 1,200 pounds.
  • A subsequent subadult phase lasting 10 to 15 years points to prolonged, slower growth that likely altered ecological roles over time.
  • Authors report that standard ageing protocols may need revision and note taxonomic uncertainty within a possible T. rex species complex, including outliers such as “Jane” and “Petey.”