Recently Discovered Dinosaurs: New Species That Are Rewriting Prehistory

About 50 new dinosaur species are named every year. This has been roughly true for the past couple of decades, and the rate is, if anything, accelerating. We have named around 1,000 valid dinosaur genera — and current estimates suggest we’ve found perhaps 30% of the genera that actually existed. The majority of what’s left to find is probably smaller animals, which preserve less reliably, but the large predator and sauropod discoveries keep coming too. The golden age of dinosaur palaeontology is not in the past.

Here are some of the more significant recent finds, and what they tell us about the Mesozoic world.

Meraxes (2022): The Case of the Tiny Arms

Named after a dragon from George R.R. Martin’s A Song of Ice and Fire, Meraxes gigas was a carcharodontosaurid — the same family as Giganotosaurus — and about 11 metres long, which is substantial. What made the 2022 description scientifically notable was what it showed about the arms.

Like T-Rex, Meraxes had very short forelimbs relative to its body. But tyrannosaurs and carcharodontosaurids are not closely related — they evolved from different lineages and arrived at similar body plans through convergent evolution. Carnotaurus, an abelisaurid from the same region, did the same thing. Three separate large predator lineages, independently, ended up with very small arms.

This is telling. If tiny arms were simply a “leftover” from some earlier ancestor and evolutionary pressure to change them was neutral, you’d expect different lineages to end up with different arm sizes by chance. All three converging on the same solution suggests the small arms were actively advantageous — most likely because carrying heavy, muscular arms forward was worse for a skull-dominated predator than not carrying them. The skull did the work; the arms just got in the way.

Meraxes is also one of the most complete carcharodontosaurid specimens ever found, which makes the arm comparison possible in the first place.

Jakapil (2022): Armoured and Bipedal in the Wrong Place

Jakapil kaniukura was only about 1.5 metres long and 5 kilograms — small enough to fit in a shopping trolley — but its significance is disproportionate to its size. It’s a thyreophoran, the group that includes Stegosaurus and Ankylosaurus, and it lived in South America during the Late Cretaceous, roughly 97 million years ago.

The problem with this is that thyreophorans were supposed to have been absent from South America by the Early Cretaceous. Jakapil pushes their presence in the southern continents tens of millions of years later than the previous record. It means either the group survived there in a long ghost lineage that left no earlier fossils, or they crossed from another landmass later than expected. Either option complicates the established story of thyreophoran biogeography.

Jakapil was also apparently bipedal — all known thyreophorans were quadrupedal, so this is another oddity. Small armoured biped, armour rows along the neck and back, living where it wasn’t supposed to be, later than expected. Sometimes a five-kilogram animal causes more scientific disruption than a giant sauropod.

Halszkaraptor (2017): The Raptor That Went Swimming

Halszkaraptor escuilliei from Late Cretaceous Mongolia was a dromaeosaurid — the family that includes Velociraptor — but it was apparently semi-aquatic, which nothing in the family was supposed to be.

The specimen was studied using synchrotron X-ray imaging while still embedded in its rock matrix, which allowed researchers to examine its internal anatomy without physically extracting and potentially damaging it. The results showed a swan-like elongated neck with anatomy consistent with fishing behaviour, flipper-shaped forelimbs, and sensory pits in the snout similar to those crocodilians use to detect prey movement in water. It was about 60 centimetres long, so nothing was going to be terrified of it, but the ecological inference is genuinely surprising.

The Dromaeosauridae were supposed to be small to medium terrestrial predators. Halszkaraptor suggests the actual range of ecological niches they occupied was wider than the fossil record had indicated.

Bajadasaurus (2019): Forward Spines

Bajadasaurus pronuspinax from Early Cretaceous Argentina had extremely long spines projecting forward from its neck vertebrae. Not upward, as in Spinosaurus. Forward, over the neck itself. This is anatomically bizarre and not clearly paralleled in any other known dinosaur.

The function is genuinely uncertain. Defence against predators attacking the neck is the most intuitive explanation — the spines would have made it very difficult to bite into from above. Display and thermoregulation have also been proposed. Bajadasaurus was a dicraeosaurid sauropod, a relatively unusual family with shorter necks than the more familiar diplodocids, and apparently a much stranger appearance.

Meraxes, Maip, and Patagonia’s Ongoing Fossil Output

It’s worth noting how much of recent dinosaur palaeontology is coming from Patagonia. Maip macrothorax, a large megaraptorid from about 70 million years ago named after a Patagonian mythological figure, was described in 2022 alongside Meraxes and Jakapil. The region produces significant new finds with unusual regularity, partly because of the quality of Cretaceous sedimentary exposures there and partly because of growing local palaeontological research capacity.

The giants that have come out of Argentina — Argentinosaurus, Patagotitan, Giganotosaurus, Mapusaurus, Dreadnoughtus — represent some of the most important dinosaur specimens of the last three decades. There is probably more to come.

How Many Are Left to Find?

The estimate that we’ve found around 30% of all dinosaur genera is based on statistical modelling of the discovery rate curve — as more species are found, the rate of genuinely new genera relative to total finds allows you to extrapolate toward a total. The methodology has been refined several times, and different studies give slightly different numbers, but the general conclusion is consistent: most dinosaur diversity is still in the ground.

What we’re likely to find more of is smaller animals. Small dinosaurs preserved less readily than large ones — their bones were more fragile, they were less likely to be buried before being destroyed, and they’re harder to spot in the field. The feathered microfossils from Liaoning Province in China, preserved in fine-grained lake sediments with extraordinary detail, give a glimpse of the small-animal diversity that’s largely invisible in coarser fossil beds. Those deposits are unusual. Most environments don’t preserve at that resolution.

New technology is expanding what we can recover even from known specimens. Synchrotron imaging, as used on Halszkaraptor, can reveal internal anatomy impossible to see by surface preparation. Protein analysis is beginning to recover biological molecules from fossil bone that survive far longer than DNA. Photoluminescence techniques can sometimes recover colour patterns from melanosomes preserved in fossil feathers. The specimens already in museum drawers may have more to tell us than we’ve yet extracted.