How Big Was Spinosaurus Compared to T. rex and a Human?

In the most recent full reconstruction, an adult Spinosaurus was just under 14 m (46 ft) long and weighed about 7.4 tonnes (8.1 short tons) (Sereno et al. 2022). Laid out on the ground, that is about eight adult humans head to toe, and a little longer than a large T. rex.

It is also one of the most revised sizes in palaeontology. Below is the human-scale picture, then why the estimates have moved.

Spinosaurus vs a human at a glance

• Length: Spinosaurus about 13.5 to 14 m (44 to 46 ft); an adult human about 1.7 m (5 ft 7 in).
• Weight: Spinosaurus about 7,390 kg (16,300 lb) in one volumetric model; roughly a hundred adult people.
• Hip height (estimated, very low confidence): about 2.2 to 3 m (7.2 to 9.8 ft), so a person would reach about its thigh.
• Sail: tall spines on its back added height above the hips; how tall depends on the reconstruction.

How big was Spinosaurus next to a person?

Length is the easiest comparison. Sereno and colleagues (2022) built a digital skeleton and gave "just under 14 m" standing, about 13.5 m in a swimming pose. Lay eight people end to end and you have a Spinosaurus.

Height is harder. Spinosaurus had short hind legs for its length, so its hips were lower than you might expect for such a long predator. The DinoDex estimate of 2.2 to 3 m is scaled from the short hind limb of a subadult skeleton and flagged very low confidence, so we treat it as a rough picture: an adult human would stand about as high as the top of its thigh, with the back and sail rising well above.

How big was Spinosaurus compared to T. rex?

• Length: Spinosaurus 13.5 to 14 m; T. rex about 12.3 m for "Sue" (Brochu 2003), up to about 13 m reported for the largest.
• Weight: Spinosaurus about 7.4 t; most adult T. rex about 6 to 8 t, Sue about 9.5 t (Hutchinson et al. 2011).
• Hip height (estimated): Spinosaurus 2.2 to 3 m; T. rex 3.6 to 4 m (11.8 to 13.1 ft).

Measured against a 12 m (40 ft) city bus, both animals are longer than the vehicle, but a Spinosaurus would overhang it by more.

So Spinosaurus was probably longer, but lower and built lighter for its length; T. rex stood taller at the hip and was bulkier. We compare the rest, from skulls to diet, in T. rex vs Spinosaurus.

Why did Spinosaurus size estimates change?

Because the evidence has changed three times.

The lost original. Ernst Stromer described Spinosaurus in 1915 from a partial skeleton found in the Bahariya Formation of Egypt. It was destroyed in Munich in 1944, leaving drawings and photographs.

Scaling from a snout. Cristiano Dal Sasso and colleagues (2005) described a large partial snout and scaled it to a whole animal, producing a larger animal than later reconstructions. Scaling from a skull fragment assumes the body kept the proportions of its relatives, and Spinosaurus turned out not to.

A new skeleton. In 2014, Nizar Ibrahim and colleagues described a subadult skeleton from the Kem Kem Group of Morocco, now the neotype, with short hind legs and a long trunk. Sereno et al. (2022) used it with other material for the 13.5 to 14 m model. Different reconstructions still disagree, so the DinoDex profile shows the 2022 model as a range and records the older figures in its notes instead of averaging them.

What would it be like to stand next to one?

You would notice the head first. Spinosaurus had a long, narrow snout with conical teeth, closer to a crocodile's than to the deep skull of T. rex, suited to catching slippery prey such as fish, a large part of its diet. Behind it came a long neck and a trunk carrying the tall sail, then a deep tail. Because the hind legs were short, the body would have looked long and low compared with most giant predators, more stretched out than towering. How much time it spent in water is still debated.

When and where did Spinosaurus live?

In the rivers of North Africa during the Cenomanian, about 100 to 94 million years ago, some 26 to 34 million years before T. rex. For its world, see where did Spinosaurus live?

Quick answers

• How long was Spinosaurus? Just under 14 m (46 ft) in the 2022 reconstruction, about eight adult humans head to toe.
• Was Spinosaurus bigger than T. rex? Longer, probably; heavier, not clearly.
• How tall was Spinosaurus? Its estimated hip height is 2.2 to 3 m, very low confidence; the sail rose higher.