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Purussaurus brasiliensis
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Purussaurus brasiliensis is an extinct species of giant caiman that lived in South America during the Miocene epoch, 20.4 to 5.3 million years ago. It is known from skull material found in the Brazilian and Peruvian Amazon, Colombian Villavieja Formation, Panamanian Culebra Formation and the Urumaco and Socorro Formations of northern Venezuela.
The largest specimen is a partial mandible (DGM 527-R) is estimated at 175 cm when complete. Based on a modern-day relative (the American alligator), Purussaurus has been estimated at 10-11 meters in length and 7000-8000 kg, similar to modern elephants in size and among the largest crocodilians ever. However, as only skulls have been found this is not entirely certain. The largest known Purussaurus specimens probably had a bite force of 93830 newtons (9570 kg), giving the animal a very powerful bite for its size and among the strongest bites in the animal kingdom, even stronger than modern estimates for the bite force of Tyrannosaurus rex. The teeth, although designed for executing a high bite force over cutting flesh, have small ridges along two of the edges which resemble those in ziphodonts. This indicates that Purussaurus hunted large vertebrates, as these ridges are used for puncturing and holding on to flesh. They are slightly flattened at the top and are roughly conical, which means that they would have been unlikely to break on impact with a thick bone. The large size and estimated strength of this animal appears to have allowed it to include a wide range of prey in its diet, making it an apex predator in its ecosystem. As an adult, it would have preyed upon large to very large vertebrates such as the xenarthrans and notoungulates present, with no real competition from sympatric, smaller, carnivores. Researchers have proposed that the large size of Purussaurus, though offering many advantages, may also have led to its vulnerability. The constantly changing environment on a large geological scale may have reduced its long-term survival, favoring smaller species more resilient to ecological shifts. In other words, it was over-specialised and couldn't survive when its habitat changed, unlike smaller related species of caiman. 
I feel like I gotta drop this post here too.
The Brazilian Tyrannosaurus year: 2019 https://www.oeco.org.br/reportagens/o-ti...rasileiro/ A little over a month ago, in early July, a curious event took place in the municipality of Brasiléia, in the state of Acre - Brazil. Robson Cavalcante, an 11 year old boy was fishing with his father on a bank of the Acre River when he stepped on something strange. "I was fishing then I stepped on something different and called my father. He dug a little and I thought it was a dinosaur" said the boy. The father of the kid, the carpenter José Militão returned to the site the next day to dig further and was impressed with what he found: "I used a hoe and a pick and I discovered that it happened to be a fossil. I did it very carefully so as not to damage it." What Robson had found was not a dinosaur. Nevertheless it was the remains of a monster. It was the lower jaw of a Purusaurus, the largest Caiman that ever lived. The news of the discovery of a dinosaur spread through the streets of Brasiléia. It didn't take long for the rumor to spread more than 200 kilometers away, in the state capital, Rio Branco, more specifically in the Paleontology Laboratory of the Federal University of Acre (UFAC). This is how paleontologist Jonas Filho learned about the find and he went to investigate it. "It's a purussaurus caiman, one of the largest that ever existed in the Amazon, about 8 million ago. It's a complete jaw. It seems that besides the jaw it has a skull that is being exposed" said the paleontologist. The fossilized jaw is more than a meter long which gives the dimensions of the scary mouth that the animal had. The boy Robson and his father inside the lower jaw of a Purussaurus. Photo: Personal file/Raylanderson Frota.  *This image is copyright of its original author In the following days, Jonas Filho carefully collected the block of rock containing the fossil and transported it from the banks of the Acre River to the workbench in his laboratory. There the newly discovered fossil became part of the collection of Purusaur bones that paleontologists in Acre have been collecting for decades. The star of the collection is a complete skull, the only one ever discovered, a magnificent specimen one and a half meters long, half a meter wide and another half meter high. The skull was found in the 1980s in the ravines of the Acre River by a team of Brazilian paleontologists (from UFAC) and American paleontologists from the Natural History Museum in Los Angeles. The fossil is so big and heavy - estimated to be over a ton - that to remove and transport it, it had to be cut into several parts, which were glued back together in the laboratory. The removal of all the rock surrounding the skull was a work of many months, carried out by experts in Los Angeles. When the fossil was finally released from the rock, the result proved impressive. The first complete skull of a purusaur is imposing and frightening. It is in no way less impressive than those skulls of tyrannosaurus rex, the most famous of all dinosaurs, which lived in North America dozens of millions of years before the purusaurus. After being studied, the complete skull of the purusaurus returned to Acre where it has been kept for more than thirty years under an acrylic dome in the exhibition room of the Paleontology Laboratory of the UFAC, in Rio Branco. Since then, replicas of that stupendous skull have been modeled and exhibited in several natural history museums around the world. But the original one is in Acre - Brazil. Complete skull of Purusaurus at the Laboratory of Paleontology Federal University of Acre - Brazil. Photo: Peter Moon.  *This image is copyright of its original author
Apologies for deleting and reposting this for the third time. I really don't want to make it seem like spam but I've gotten so much new information since I made the last post that it had to be redone.
I actually got the chance to ask Jorge W. Moreno-Bernal about the 2007 abstract, in the comments of here. As he wrote: Quote:As you point out, the Dorsal Skull length I provided for Purussaurus brasiliensis UFAC 1403 (134) cm was incorrect, as it was an estimate I made from published total and basal skull lengths. Now I have a direct measurement of the dorsal length, kindly provided by a Brazilian colleague. This measured (and not yet published) value of dorsal skull length is several centimeters shorter than my 2007 estimate of 134 cm. The problem this causes for estimating the size of Purussaurus is some major uncertainty in terms of mandible measurements (UFAC 1118 in particular). Aguilera et al. (2006) report the UFAC 1118 mandible as 159.5 cm, but I am very skeptical of this measurement, for 2 reasons: -They worked with casts, as they wrote under Figure 5. But casts can be rather fickle, shrinking to a degree from the real bone especially as they get larger. In this case, we don't know if they were cast separately or not, nor whether the temperature change and therefore shrinkage was consistent between them. -The mandible/dorsal skull length ratio in those casts is not consistent with the figures in Aureliano et al. (2015), and nothing I could find seemed to indicate those figures being drawn from casts instead of the real bones. So what I think is by far the most likely is that the Aguilera et al. (2006) measurements are from mismatched casts while the Aureliano et al. (2015) figures are the most accurate representation of the specimens. -This gives another contradiction. Moreno-Bernal states that the dorsal skull length of UFAC 1403 is smaller than 134 cm, yet even assuming that dorsal skull length, UFAC 1118 comes out well below 159.5 cm (143.8 to be precise) - more reason still to suspect the casts Aguilera et al. used are mismatched in terms of shrinkage, as a lower dorsal skull length than 134 cm only brings the mandible's measurement further down. But we're not out of the woods yet. Given the aforementioned problems with the published measurements as well as some now known to be explicitly incorrect, the skull length of UFAC 1403 and mandible length of UFAC 1118 aren't exactly deductible at this time, so unlike in the last post, I will not be attempting to measure or estimate their size and will have no opinion on it unless or until more consistent measurements are published. I also do not have any opinion on what the biteforce of Purussaurus could have been, because all the above makes it anything except easy to estimate. What I will be using for size estimates is the mandible DGM 527-R, which Aguilera et al., Aureliano et al., and Moreno-Bernal all appear to agree with on the 175 cm estimated length. In order to avoid any problems with published measurements, it will be estimated directly from the mandible length of the American alligator. Mandible length and body size of the base alligator: Bailleul et al. (2016) provides the skull length of a 3.3 meter alligator (ROM R4411) as 44.5 cm. I could not find in the paper how this measurement was taken, so I will tentatively assume it represents dorsal cranial length, which is almost always used for crocodilian skulls. Campione & Evans (2012) give the body size of this alligator as 168 kg. No mandible length was given for this specimen, but that can be inferred from other alligator skulls. For example, based on the alligator skull in Erickson et al. (2012), the dorsal skull length is around 91% of the mandible length, so the mandible of ROM R4411 was probably around 48.9 cm. Size estimate for Purussaurus: Assuming the figures for ROM R4411 as written above are accurate, DGM 527-R would be 11.8 meters and 7700 kg assuming isometry with mandible length. This is about the same as my previous weight estimate but somewhat shorter in length. Conclusions: -UFAC 1403 and UFAC 1118 probably cannot be estimated at this time, we don't have consistent measurements. -DGM 527-R, by contrast, can be estimated. It comes out very similar in size to my older estimates and quite large to boot. -Bite force would certainly be very high, but how high is uncertain. Note that this post is prone to updates and/or complete deletion and revision as I learn more. |
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