|Name Meaning||Abel’s Lizard||Height||2.1 meters (7 feet)|
|Pronunciation||Ah-bell-ee-sore-us||Length||7.2 to 11 meters (23.6 to 36 feet)|
|Era||Mesozoic – Late Cretaceous||Weight||1.65 to 3 metric tons (1.8 to 3.3 short tons)|
|Classification||Dinosauria, Saurischia and Theropoda||Location||Argentina, South America|
Abelisaurus was a carnivorous theropod. The genus is known only from an incomplete skull discovered in Argentina in 1983.
The genus and its only species, Abelisaurus comahuensis, were named and described in 1985.
Although they are now placed in the Abelisauridae family, many paleontologists believe that Abel’s lizards were, in fact, carcharodontosaurids.
These theropods were quite large, probably making for excellent apex predators in their ecosystem.
Imagine that their skulls alone measured almost 1 meter (3.3 feet) long!
As such, Abelisaurus may have targeted the herbivores roaming through Argentina – maybe even the large sauropods!
Are you curious to learn more? Keep reading, as we’ve got plenty of interesting facts!
Abelisaurus is known only from skull fossils, which is why scientists focused their studies primarily on outlining skull morphology.
Therefore, the postcranial skeleton of Abelisaurus is poorly known.
However, we’ll try to outline a possible appearance based on what is known about other members of the Abelisauridae family.
Scientists estimated that Abelisaurus had a skull length of approximately 85 centimeters (33.5 inches).
It featured distinctive rough ridges above the eyes and on its snout.
This makes the genus stand out among other abelisaurids, which had bony crests or horns instead of ridges.
Furthermore, scientists do not rule out the possibility that these ridges supported a kind of keratin crest, which may have been lost during the fossilization process.
Like other dinosaurs, Abelisaurus had large fenestrae in the skull, which had the goal of reducing skull weight.
While most theropod skulls had a tapered snout, Abelisaurus and other abelisaurids had blunt snouts.
Scientists could estimate a possible Abelisaurus body length and weight based on the skull length.
Some proposed a length of 10–11 meters (33–36 feet) and a weight of 3 metric tons (3.3 short tons), while others reduced these numbers to 7.2–7.4 meters (23.6–24.3 feet) and 1.65 metric tons (1.81 short tons).
The hip height was estimated at 2.1 meters (7 feet).
Abelisaurids are known to have had four-fingered forelimbs.
They probably walked with their arms held straight, considering that their elbow joints weren’t flexible.
The first and fourth digits were also immobile.
On the other hand, other abelisaurids like Noasaurus evolved to have longer and more flexible forelimbs and fingers.
Therefore, since no Abelisaurus forelimbs were recovered, we aren’t entirely sure of their limb morphology.
But can you blame us for guessing? After all, so many aspects of our world’s prehistory are pure speculation!
Abelisaurus comahuensis may be synonymous with Aucasaurus garridoi.
If this is true, the specimen used to describe this species was much smaller, and, considering its body length, the forelimbs were proportionally longer.
Still, the synonymity hasn’t been fully accepted yet, so these assumptions remain, again, only assumptions!
Habitat and Distribution
It remains unknown where exactly Abelisaurus fossils have been recovered from.
Some sources list it as belonging to the Allen Formation, while others mention that the skull was recovered from the Anacleto Formation.
Considering that no witnesses who had been present on the site are alive, it is difficult to understand which territory served as its home.
This may also influence the temporal range of Abelisaurus since the Allen Formation dates from 73-69 million years ago, while the Anacleto Formation dates from 83-74.5 million years ago.
However, the two formations probably featured similar environments, such as fluvial, lacustrine, and aeolian.
The climate was likely warmer than it is today, although cooling trends occurred.
Behavior and Diet
Abelisaurus was a bipedal carnivore.
Like other theropods, it may have been an apex predator in its habitat.
Scientists argue that Abelisaurus fed on sauropods like Barrosaurus, Neuquensaurus, and Antarctosaurus.
It may have also been a scavenger, but this hasn’t been fully confirmed yet.
Some sources mention that Abelisaurus was quite solitary but did not refuse group hunting if the opportunity presented itself.
This hunting strategy may have been highly efficient if they went for large sauropods like Barrosasaurus or Antarctosaurus, which reached lengths of 17-18 meters (55.8–59 feet)!
Since its eyes did not face forward like in some tyrannosaurids, Abelisaurus probably did not rely much on its eyesight to catch prey.
Instead, it may have been a fast runner, considering that its forelimbs may have been robust enough to acquire a high speed.
If Abelisaurus’s hind limbs resembled those of a Carnotaurus, it may have been able to attain speeds of 48-56 km/h (30-35 mph).
Apart from these details, little else is known about the behavior, lifestyle, and dietary or hunting preferences of Abelisaurus theropods.
Like other dinosaurs, Abelisaurus reproduced by laying eggs.
Studies on the theropod reproductive system showed that males had a retractable penis and internal testes.
Females had paired ovaries and oviducts and laid two eggs at a time.
Additionally, females probably had a crocodilian-like system that served as a storage space for eggs awaiting fertilization.
It remains unknown whether Abelisaurus incubated the eggs, but this behavior has been confirmed in at least some theropod groups.
If incubation occurred, it probably lasted between 60 and 90 days.
Many baby dinosaurs are known to be precocial, which means they were quite developed and could fend for themselves within a few days or even hours after hatching.
Studies on abelisaurid ontogeny and growth showed that abelisaurids grew much slower than other theropods.
Some required approximately 20 years to reach the maximum size.
It is known that, although well-developed upon hatching, precocial animals grow much slower throughout their lives and reach sexual maturity later than altricial animals.
As such, we may assume that abelisaurid babies, including those of Abelisaurus, may have been precocial.
Evolution and History
The Abelisauridae family is classified under the Ceratosauria group of theropods, which appeared during the Early Jurassic.
As they evolved and diversified, ceratosaurs competed with the more specialized tetanurans.
Abelisaurus comahuensis is the type species of the Abelisauridae family.
Both were named in honor of Roberto Abel.
It is currently believed that the basalmost position of the Abelisauridae family is held by Eoabelisaurus, which inhabited Argentina approximately 179-178 million years ago.
As such, Abelisaurus is separated from the oldest abelisaurid by almost 100 million years!
The Abelisauridae family consists of two groups of dinosaurs: Carnotaurinae and Majungasaurinae.
Abelisaurus is part of the former and further placed into Furileusauria and Carnotaurini.
Additionally, a separate group called Abelisaurinae has been formed to comprise Abelisaurus and the possibly synonymous Aucasaurus.
Abelisaurus fossils were introduced to the paleontological universe in 1983 when Robert Abel discovered an incomplete skull in the Lago Pellegrini quarries.
Robert Abel was also the director of the Argentinian Carlos Ameghino Provincial Museum, where the Abelisaurus skull is currently on display!
In 1985, Fernando Emilio Novas and Jose Bonaparte used the fossilized skull to name the genus and species Abelisaurus comahuensis.
As already mentioned, it remains unknown to which formation the Abelisaurus fossils truly belong.
Is it the Allen Formation or the Anacleto Formation? Hopefully, future findings will unravel the mystery!
Gregory S. Paul, an American researcher who works in the field of paleontology, argued that Aucasaurus, a medium-sized abelisaurid discovered in the Anacleto Formation, is synonymous with Abelisaurus.
The fossils belonging to these two theropods did indeed share multiple characteristics, but they are still classified as separate taxa.
Since the discovery of Abelisaurus, paleontologists recovered multiple other abelisaurid genera known from more complete skeletons.
Abelisaurus shares many traits with carcharodontosaurids (Carcharodontosauridae), and some studies suggest it may have been, in fact, a late-surviving carcharodontosaurid derivative.
They’ve suggested that future fossil discoveries will prove this theory. Until then, Abelisaurus remains an abelisaurid!
Interactions with Other Species
Late Cretaceous Argentina was abundant in dinosaurs, including sauropods, ornithischians, and theropods.
Crocodylomorphs like Gasparinisuchus and Peirosaurus, snakes like Dinilysia, and turtles like Prochelidella and Yaminuechelys were quite common as well.
However, Abelisaurus probably did not pay any attention to crocodylomorphs or snakes! They were rather focused on herbivores that could serve as meals!
The herbivorous dinosaur population of the Anacleto Formation was represented by sauropods and ornithischians.
Therefore, Abelisaurus may have preyed on any of the following genera:
The largest herbivores were likely Antarctosaurus and Barrosasaurus. They were twice as large as Abelisaurus, so the carnivore may have struggled a bit to subdue them; that is, if it ever aimed at killing them.
If Abelisaurus hunted in packs, they had higher chances of delighting in a giant sauropod meal!
On the other hand, let’s not forget that the temporal range of Abelisaurus hasn’t been fully confirmed yet, so it may not have crossed paths with all the herbivores mentioned above.
Argentina was home to other carnivorous theropods besides Abelisaurus, which may have caused a certain degree of competition for food.
If Abelisaurus was recovered from the Allen Formation, it may have had a much more interesting life, as the territory was richer in prehistoric creatures!
It served as a home to frogs, mammals, plesiosaurs, sphenodonts, pterosaurs, and various fish species!
Abelisaurus was the first abelisaurid to be named and described, so its importance in paleontology is indisputable.
Considering that the description was based on a single incomplete skull, we cannot deny the fact that scientists did tremendously well in outlining its distinctive characteristics, behavior, lifestyle, and dietary preferences.
Needless to say, new paleontological discoveries are of the essence in learning more about this Late Cretaceous theropod of Argentina.
Luckily for dinosaur enthusiasts, the original skull of Abelisaurus is on display at the Carlos Ameghino Provincial Museum.
The museum is located in the city of Cipolletti, in Argentina’s Rio Negro Province.
If you live in Argentina or are planning a trip to southern South America, don’t hesitate to check out these fossils dating from almost 100 million years ago!
Abelisaurus comahuensis is the only species in the Abelisaurus genus. It was recovered from Argentina in 1983.
Scientists believe it was an inhabitant of the Patagonian territory during the Late Cretaceous, although they aren’t entirely sure of a precise timeline of existence.
Abel’s lizard was a large theropod measuring approximately 7.4 meters (24.3 feet) in length, although some estimations go up to 11 meters (36.3 feet).
It probably had small forelimbs, similar to those of Carnotaurus and Tyrannosaurus, and may have relied on its running abilities to catch prey.
Considering what other animals were discovered on the same territory, we suppose that Abelisaurus was fond of hunting sauropods.
They may have evolved to hunt in packs, targeting the largest herbivores.
Now that we’ve reached the end of this article, we’d like to ask you the following question: Can you imagine that so many details were outlined based on a single incomplete skull? How fascinating is this?
What was the biggest abelisaurid?
Pycnonemosaurus is currently considered the largest abelisaurid. It measured 8.9–9 meters (29.2–29.5 feet) long and weighed 1.2–3.6 metric tons (short tons).