Spinosauridae
Large, fish-eating theropods with crocodile-like skulls and often a sail.
Spinosauridae, also called spinosaurids, is a group of tetanuran theropod dinosaurs that contains between ten and seventeen known genera. Their fossils have turned up across Africa, Europe, South America, and Asia, and date from the Early to Late Cretaceous. These were large, bipedal meat-eaters. Their skulls were long, low, and narrow, resembling a crocodile’s, with conical teeth that had little to no serrations. The tips of both upper and lower jaws widened into a spoon-like rosette, and behind that the upper jaw had a notch that the lower jaw’s expanded tip fit into. Their nostrils sat farther back on the head than in most other theropods, and they had bony crests running along the midline of the skull. Their shoulders were robust, with stocky forelimbs and three-fingered hands that carried an enlarged claw on the first digit. In many species, the neural spines of the vertebrae were greatly elongated, rising upward to form a sail on the back—hence the family’s name—which likely supported either skin or a fatty hump.
The genus *Spinosaurus*, which gives its name to the family, one subfamily (Spinosaurinae), and one tribe (Spinosaurini), ranks among the largest known land predators in the fossil record. It may have reached up to 14 meters (46 feet) in length and weighed as much as 7.4 metric tons (8.2 short tons). The closely related *Sigilmassasaurus* might have been similar or even larger, though its classification is disputed. Direct fossil evidence and anatomical features show that spinosaurids ate fish at least some of the time, and other finds indicate they also preyed on dinosaurs and pterosaurs. The structure of their teeth and bones suggests a semiaquatic lifestyle for some members, supported by traits like retracted eyes and nostrils, and in certain species a deeper tail that may have helped with underwater propulsion, much like modern crocodilians. Spinosaurs are thought to be closely related to the megalosaurid theropods of the Jurassic, sharing features such as an enlarged claw on the first finger and an elongated skull. However, some researchers argue that this group (Megalosauroidea) is paraphyletic, placing spinosaurs as either the most basal tetanurans or as basal carnosaurs less derived than megalosaurids.
Quick Facts
- Taxon
- Spinosauridae
- Type Species
- Spinosaurus aegyptiacus
- Type Species Authority
- Stromer, 1915
Facts from the source article.
Lore & Background
The first spinosaurid fossil, a single conical tooth, was discovered circa 1820 by British paleontologist Gideon Mantell in the Tilgate Forest area, attributed to the Wealden Group (Hastings Beds or Tunbridge Wells Sand Formation). In 1841, naturalist Sir Richard Owen mistakenly assigned it to a crocodilian he named Suchosaurus. The spinosaurid nature of Suchosaurus was not recognized until a 1998 redescription of Baryonyx. The first fossils referred to a spinosaurid were discovered in 1912 at the Bahariya Formation in Egypt, becoming the holotype of Spinosaurus aegyptiacus in 1915, described by German paleontologist Ernst Stromer. That holotype was destroyed in April 1944 during a bombing raid in World War II. In the 1990s and 2000s, Paul Sereno and colleagues described spinosaurid remains from the Elrhaz Formation of Niger, including the species Spinosaurus maroccanus (later disputed) and the related Suchomimus. As of 2024, the named spinosaurid species from the Iberian Peninsula include Baryonyx, Camarillasaurus, Vallibonavenatrix, and Riojavenatrix lacustris.
Reader's Guide
Spinosauridae represents a distinctive clade of theropod dinosaurs that evolved a semiaquatic lifestyle, as indicated by retracted eyes and nostrils, deepened tails in some taxa, and osteological adaptations. Their crocodilian-like skulls with terminal rosettes and conical teeth suggest a diet heavily reliant on fish, though fossil evidence also shows they fed on other dinosaurs and pterosaurs. The family includes some of the largest known terrestrial predators, with Spinosaurus reaching up to 14 meters in length and 7.4 metric tons. The consistency in large body size among spinosaurids may have evolved as a byproduct of their semiaquatic habits, reducing competition with other large theropods. Their relationship to other theropods is debated: some consider them closely related to megalosaurids within Megalosauroidea, while others propose they are basal tetanurans or basal carnosaurs. The discovery of Baryonyx in 1986 greatly expanded understanding of spinosaurid anatomy, and subsequent finds continue to clarify their diversity and paleobiology. The family's name derives from the elongated neural spines of many species, which formed a sail or hump on the back.
Did You Know?
- The first spinosaurid fossil, a tooth, was discovered circa 1820 by Gideon Mantell and later misidentified as a crocodilian by Richard Owen.
- The holotype of Spinosaurus aegyptiacus was destroyed in April 1944 during an allied bombing raid in World War II.
- Spinosaurid brains, based on endocasts of Baryonyx and Ceratosuchops, were similar to those of other non-maniraptoriform theropods.
- The 'White Rock spinosaurid' from the Isle of Wight (2021) is one of the largest theropods ever found in Europe.
Frequently Asked Questions
What is Spinosauridae?
Spinosauridae is a family of large, bipedal theropod dinosaurs from the Cretaceous, best recognized for their elongated, crocodile-like skulls and, in several members, a distinctive sail along the back.
What did Spinosauridae eat?
These theropods were primarily piscivorous, using long, narrow jaws lined with conical, minimally serrated teeth to seize slippery fish. The spoon-shaped widening at the jaw tips and a matching interlocking notch between upper and lower jaws helped them lock onto prey.
Where have Spinosauridae fossils been found?
Fossil material has turned up across Africa, Europe, South America, and Asia, making this one of the most geographically widespread theropod groups of the Cretaceous.
How many genera are in Spinosauridae?
The family currently includes somewhere between ten and seventeen recognized genera, though the exact number fluctuates as new specimens are described and reclassified.
When was the first Spinosauridae fossil discovered?
The earliest known discovery traces back to roughly 1820, when Gideon Mantell found material in the Tilgate Forest area of England, later linked to the Wealden Group.
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