Dating in paleontology
But in other respects Tyrannosaurus’ skull was significantly different from those of large non-tyrannosauroid theropods.It was extremely wide at the rear but had a narrow snout, allowing unusually good binocular vision.At 18 years of age, the curve plateaus again, indicating that growth slowed dramatically.For example, only 600 kg (1,300 lb) separated the 28-year-old "Sue" from a 22-year-old Canadian specimen (RTMP 81.12.1).The skull bones were massive and the nasals and some other bones were fused, preventing movement between them; but many were pneumatized (contained a "honeycomb" of tiny air spaces) which may have made the bones more flexible as well as lighter.
The remaining teeth were robust, like "lethal bananas" rather than daggers; more widely spaced and also had reinforcing ridges.
In contrast the hind limbs were among the longest in proportion to body size of any theropod.
The tail was heavy and long, sometimes containing over forty vertebrae, in order to balance the massive head and torso.
Tyrannosaurus rex was one of the largest land carnivores of all time; the largest complete specimen, FMNH PR2081 ("Sue"), measured 12.8 metres (42 ft) long, and was 4.0 metres (13 ft) tall at the hips. rex formed a natural S-shaped curve like that of other theropods, but was short and muscular to support the massive head.
The forelimbs were long thought to bear only two digits, but there is an unpublished report of a third, vestigial digit in one specimen.