Site Nº 001 · Cretaceous Apex Predator
Cretaceous · N. Africa · 99 Mya

spinosaurus.bet

Specimen File · Aegyptiacus

Anatomy of an apex predator

The full skeleton with every bone labelled. Drag to rotate it, then open any file below. Figures are measured from real fossils, not guesswork.

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Spinosaurus aegyptiacus · skeletal cast
Drag to rotate
Lived
99 to 93 Mya
Found in
North Africa
Diet
Piscivore
Filed by
Stromer, 1915
Vol. IBahariya · Munich

The Fossil Record

The Discovery

A German Names the Largest Predator the World Has Seen

Prof. Ernst Stromer returns from the Egyptian desert with the bones of a sail-backed giant he calls “Spinosaurus,” longer than any flesh-eater yet known

By our Palaeontology Correspondent

Ernst Stromer beside a fossil bone
Prof. Ernst Stromer, 1871 to 1952

German palaeontologist Ernst Stromer uncovered the first Spinosaurus bones in the Egyptian desert in 1912 and gave the giant its name in 1915. Working out of the Bahariya Oasis with the fossil collector Richard Markgraf, he drew a whole lost world of predators up out of the sand.

The creature was unlike anything on record: a fish-eater longer than a city bus, its back crowned with a sail of skin more than a metre and a half high. It would take almost a century for science to catch up with what he had found.

The bones that vanished

Then history turned on him. An outspoken opponent of the Nazis, Stromer was pushed into retirement in 1937. He pleaded with the museum in Munich to move his fossils to safety. The director, a party loyalist, refused. On the night of 24 to 25 April 1944, RAF bombers struck the building and the only Spinosaurus skeleton on Earth was destroyed.

Two of his three sons died on the Eastern Front; the last came home from a Soviet camp in 1951, and Stromer died a year later. For almost seventy years, all that survived of Spinosaurus were his careful drawings, until new bones finally surfaced in the Moroccan desert.

Plate II · Field Questions

Spinosaurus,
in eight questions

The quick, sourced answers to what the world asks most about the largest predatory dinosaur: its size, its diet, that sail, and how it measures up to T. rex.

Spinosaurus aegyptiacus skeleton, lateral reconstruction
Holotype reconstruction · S. aegyptiacus
01Fig. 01
Size

How big was Spinosaurus?

14metres

Sereno et al., 2022

A 2022 study led by palaeontologist Paul Sereno put Spinosaurus aegyptiacus at about 14 metres long and 7.4 tonnes, still the longest predatory dinosaur ever found, ahead of both T. rex and Giganotosaurus.

Field Record · 001
Fig. 02
02
vs T. rex

Was Spinosaurus bigger than T. rex?

Spinosaurus15 m
T. rex12 m

In length, yes. Spinosaurus stretched to about 15 metres against roughly 12 metres for T. rex, though T. rex was heavier, more powerfully built and bit far harder.

Field Record · 002Full comparison
Fig. 03
03
Aquatic

Did Spinosaurus swim?

Probably, at least in part. A deep, fin-like tail (described in 2020), unusually dense bones and a fish-catching snout all point to a life in and around water. Whether it actively swam after prey or waded and fished from the shoreline is still fiercely debated.

Field Record · 003
Fig. 04
04
Diet

What did Spinosaurus eat?

Mostly fish. Long jaws, straight conical teeth and pressure-sensing pits at the snout let it grip slippery prey in murky water, much like a crocodile, plus smaller prey and carrion.

Field Record · 004
Fig. 05
05
The sail

What was the sail on its back for?

No settled answer. Neural spines over 1.6 m tall, bound in skin, formed the sail. Display and species recognition lead the theories, with heat regulation and fat storage also proposed.

Field Record · 005
Fig. 06
06
Discovery

Where was Spinosaurus found?

In North Africa, chiefly the Kem Kem beds of Morocco and the Bahariya Formation of Egypt, where Ernst Stromer unearthed the first bones in 1912 and named the animal in 1915.

Field Record · 006
Fig. 07
07
Speed

How fast was Spinosaurus?

Not a sprinter. Its short hind limbs suited wading and swimming rather than chasing prey across land, so it likely relied on ambush and quick bursts near the water.

Field Record · 007
Fig. 08
08
When

When did Spinosaurus live?

During the Cenomanian age of the Cretaceous, roughly 99 to 93 million years ago, tens of millions of years before Tyrannosaurus rex ever appeared.

Field Record · 008

Fossil Archive

Selected specimens

Vertebra
VertebraSpecimen S-001
Tooth
ToothSpecimen S-002
Claw
ClawSpecimen S-003
Sail spine
Sail spineSpecimen S-004
Skull
SkullSpecimen S-005

Archive Location

Western Desert
Bahariya Formation · Egypt

28° 21′ N, 28° 51′ E

Spinosaurus aegyptiacus · the apex of its time

Read the full record →Field Archive
Complete
Plate III · Excavation Log

A century of discovery

Read it like a rock face: each stratum a decade deeper, each layer the fossil that reshaped what we know, from the first Egyptian bones to the paddle tail that proved it swam.

0 mIStratum
1912Layer 01

Fossils first unearthed in the Bahariya Formation, Egypt.

6 mIIStratum
1915Layer 02

Ernst Stromer formally names Spinosaurus aegyptiacus.

13 mIIIStratum
1944Layer 03

The original holotype is destroyed in a WWII air raid on Munich.

19 mIVStratum
2005Layer 04

Dal Sasso et al. estimate a skull over 1.75 m, hinting at record size.

24 mVStratum
2014Layer 05

Ibrahim et al. publish a new skeleton, arguing for a semi-aquatic life.

31 mVIStratum
2020Layer 06

A paddle-shaped tail confirms Spinosaurus swam after its prey.