A single, scimitar-shaped bone pulled from the Sahara’s sand can look like anything until enough pieces assemble into an animal the size of a school bus.
Paleontologists excavating a distant fossil area in the central Sahara of Niger found teeth, pieces of jaws and an oversized cranial blade which eventually provided evidence of a new species: Spinosaurus mirabilis. The animal was of the notorious sail-backed family of fish-feasting predators, however, the distinctive characteristic was a protrusion off the skull in the shape of a curved sword. This crest was approximately 20 inches in height and in life, it was probably used to make the dinosaur a moving signal through the shallow areas of rivers and woody flood plains.
The finding bore the trace of the long memory of fieldwork. In the 1950s, a note by a French geologist vaguely suggested fossils in the area and the hint would be useful in a modern search to Jenguebi, a sandstone landscape bounded by dunes. The team was guided by a local Tuareg guide who rode in on a motorbike to the regions where it was either difficult to navigate or time that is necessary to gather a harvest but leave for a later season. By the time the first crest was discovered in 2019, its identity remained unclear; it was only after a re-discovery expedition and find of more crests that the anatomy would become visible as a consistent skull.
A completely 21 st century twist was put on the reconstruction back at camp. The University of Chicago paleontologist Paul Sereno said: “I’ll forever cherish the moment in camp when we crowded around a laptop to look at the new species for the first time,” The bones were scanned into three-dimensional digital forms, reassembled with electricity collected in solar panels in the desert until the crest, jaws, and snout fitted into an unrecognizable face.
The profile is like an expert made to the waterline and not to open chase on land. The jaws contained interdigitating teeth, a structure where the upper and lower rows of teeth are interlocked, making it difficult to escape predators which are moving slickly. According to co-author of the study Daniel Vidal, the effect is described: Their interdigitating non-serrated large conical teeth create a fish trap that is highly effective at piercing and capturing slippery fish in the jaws, avoiding a slide. It had a long, crocodile-like snout, and the nostrils were placed further back than usual, which would have permitted breathing with a half of the muzzle under water at the time a deliberate, steady attack was delivered.
There is only one other species of Spinosaurus that is well known, Spinosaurus aegyptiacus, named in 1915 based on a series of fossils discovered nearer to the old coast. The group became a central part of the debate on whether a large-bodied predatory dinosaur could be a true aquatic predator because many of their previous discoveries were in deposits along the Cretaceous Tethys Sea. This does not change the physical setting of that discussion S. mirabilis is found as a fossil in an inland scene, approximately 300 to 600 miles below the closest coastal shoreline approximately 95 million years ago, where rivers wound over green country rather than coastal flatlands.
“I envision this dinosaur as a kind of ‘hell heron’ that had no problem wading on its sturdy legs into two meters of water but probably spent most of its time stalking shallower traps for the many large fish of the day,” The name represents the design of the animal hunt: a massive size with a small and weaponized skull and a jaw-structure that is more fitted to grab fish than to rip off flesh.
Even the crest is not made of solid bone, and is too delicate, it would seem, to act as a battering ram. It is surface texture and internal channels that propose that it was probably covered by keratin, brightly colored in the flesh, not a weapon of battle but an articulation of display and identification in the vast feeding areas where size was not the only signal worth transmitting.
