https://scitechdaily.com/new-biomechanical-model-shows-tyrannosaurus-rex-walked-surprisingly-slowly/

https://www.livescience.com/t-rex-slow-walker-tail.html


As the title of the topic says, a new study published on April 21, 2021 shows newer estimates on how fast a Tyrannosaurus might of was. Earlier estimates (Sellers 2017) had not taken fully into account the role of the T. rex's tail - which makes up more than half its length. Pasha Van Bijlert, is the lead author of this new study on Tyrannosaurus locomotion which is published in the Journal Royal Society Open Science. Sellers 2017 bio-mechanic study had it's issues treating the Tyrannosaurus legs as if they were graviportal, posing them in a columnar manner. However, the limbs of Tyrannosaurus were not built to be graviportal, those are the legs of a cursorial animal. The research team calculated a step rhythm from a computer model of a Tyrannosaurus tail, based on Trix, an adult 12-meter-long (39-foot-long) Tyrannosaurus fossil at the Naturalis Biodiversity Center, a museum of natural history and research center in the Netherlands. The scientists then multiplied the step rhythm by the step length found in fossilized tracks for an estimated baseline walking speed of 2.86 miles per hour. This is a far cry from the proposed 11-12mph brisk walking estimates from William Sellers 2017 study. Pasha Van Bijert said:
 

"Animals tend to prefer walking speeds at which, for a given distance, energy cost is minimal. They do this choosing specific step rhythms at which their body parts resonate. Since the entire tail of T. rex is suspended by ligaments, which behave like rubber bands, we reconstructed this tail to investigate at which step rhythm the tail of T. rex would resonate. The entire tail, by our reconstruction at almost 1,000 kilos, was really just a mass supported by a rubber band and with every step it would slightly bounce up and down. With the right rhythm you get a lot of movement for very little effort. Our baseline model had a preferred walking speed of 2.86 mph [4.6 km/h], which was significantly slower than earlier estimates of walking speed. Depending on some of the assumptions regarding the ligaments and how the vertebrae rotate, you get slightly slower or faster speeds (1.79 to 3.67 mph [2.88 to 5.9 km/h]), but across the board, they're all slower than earlier estimates"


This makes me question whether or not adult sized Tyrannosaurus were capable of hunting or not. I was firm to believe that prey such as Triceratops or Ankylosaurus were just as slow but with these newer estimates I'm doubting that adult sized Tyrannosaurus did hunt. Even though the risks of hunting such prey were too high, Triceratops or Ankylosaurus were not the first thing they would go for. The size of Tyrannosaurus brain is, rather unsurprisingly, quite small in proportion to its body. But it's not its total size I'm referring to. It's the proportions of the brain itself. It's no secret that the largest portion of the brain is the olfactory lobe, the part of the brain devoted to scent processing. This new study definitely ignites evidence that adult Tyrannosaurus relied on scavenging rather than hunting compared to the juvenile ones, where speed is not that big of an issue. Finding enough dead carcasses can be rather difficult, but rotting meat can carry a scent for miles in any direction. If your a scavenger, like an old world vulture shall we say, all you have to do is point, and fly, or in T. Rex's case walk, to the source of the smell. Couldn't be easier. Also as a small point, while Old World vultures use smell to find carcasses, New World vultures often rely on their eyesight. Now we know Tyrannosaurus had some really good eyesight, so perhaps young Tyrannosaurus used it to hunt, but as they got older it could've shifted to find carcasses. Just a thought. (Credit goes to vcubestudios for the information)

A new thread dedicated just to the king as they are a species different from the rest.

The king will get you anywhere even atop trees:

This is a thread about intraspecific conflict in tigers.

Hello everyone !

I would like to know if bears can control their fingers to make different moves from each other.

Are bears able to pinch, like we, the humans are able to do ?




Can they move the 4 fingers (those other than the thumb) closer or further, by using lateral abduction or median abduction ? (shown below in the left)




THANK YOU IN ADVANCE FOR YOUR ANSWERS ,


Florin

Megaraptor ("giant thief") is a genus of unusual theropod dinosaur that lived in the Turonian to Coniacian ages of the Late Cretaceous. Its fossils have been discovered in the rocks of the Portezuelo Formation in what is now Neuquén Province, Argentina. The holotype specimen was thought to be a giant dromaeosaurid at the time of naming in 1998 due to a very large claw interpreted as belonging to the second toe (as in dromaeosaurids). A more complete specimen described in 2004, however, showed the claw to not belong to the second toe at all but rather to the first digit of the manus, nullifying the previously proposed dromaeosaurid affinities.
The manus itself was found to be quite distinct from other known theropods at the time of its discovery, so it was not initially clear whether Megaraptor belonged to any known family of Gondwanan theropods or to a new family of theropods altogether. Early phylogenetic analyses placed Megaraptor as a basal tetanuran (both as an allosauroid and a spinosauroid), with the allosauroid theory becoming more widely accepted when other close relatives of Megaraptor (like Aerosteon and Orkoraptor) were discovered and found to form the family Megaraptora with it. 
New juvenile material of Megaraptor published in 2014 has established Megaraptor (and all other megaraptorans) were tyrannosauroids instead of allosauroids or spinosauroids, and that has been upheld very well, with almost all phylogenetic analyses since then recovering them as such. But, while bearing much morphological resemblance to the primitive tyrannosauroid family Proceratosauridae, megaraptorans were unlike the well-known tyrannosaurids in that they underwent forelimb enlargement instead of reduction and had very different ecology as a result of it.
Megaraptor itself was no exception to this. It would have had large, powerfully-built forelimbs bearing three-fingered hands, with an enlarged claw on the first digit. The humerus was long and robust with a prominent deltopectoral crest, and the ulna had a hypertrophied, blade-like olecranon process, indicating the arm muscles (like the triceps and deltoids) were very well-developed for use in prey capture. The manus was very elongated to facilitate grasping of prey items, as was the first digit's claw, with the largest claws found so far being well over 35 centimeters long and quite sharp to boot. In fact, current estimates suggest the forelimbs of Megaraptor were both longer and more robust (therefore almost certainly more powerful) relative to the animal's size than the forelimbs of carnivorous mammals like big cats or bears, strongly indicating it had a need just as great as - if not greater than - said carnivorous mammals for forelimb use in prey acquisition. 
The rest of the animal showed similarities to various other tyrannosauroids. Cranial material shows the skull was long-snouted with many small and sharp teeth (similar to the primitive tyrannosauroids Dilong and Xiongguanlong), and the preserved portions of the axial skeleton show the torso would have been deep and wide (akin to derived tyrannosaurids). The hindlimbs were very distally elongated with particularly long, gracile metatarsals, no different to the nearly universal cursorial adaptations in almost all of Tyrannosauroidea, suggesting Megaraptor was probably a good runner.
Megaraptor was a large theropod. Known adult specimens were at least 6.5 meters long, and have been estimated to weigh 1000 kg by Gregory S. Paul. Owing to its size, it may have been the apex predator of the Portezuelo, dominant over the much smaller Unenlagia and unnamed abelisaurids.

This thread will cover the populations found in the forests and basins of South America north of the Amazon basin (excluding the Llanos), most predominantly the Magdalena Medio region of Colombia, the Maracaibo Lake basin of Venezuela, the Darien intersection between Colombia and Panama, the Venezuelan tepuys etc.

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Jaguars in the Magdalena Medio Valley of Colombia
These jaguars are renowned for being buffalo killers:





By Jhon Mario

Jaguars from the Maracaibo Lake Basin, Venezuela. 
These Jaguars are tracked by the Sebraba Project, the most important jaguar conservationist organization in Venezuela:

Female



Male






Jaguar from the Darien Gap in the Pacific rainforests in northern Colombia
Bordering Panama, stretching to Ecuador and Peru.





By Juan Delgado

I find tiger Konda had been confused with another tiger,but I don't know who is the tiger.and I post some Konda picture next.

Marshosaurus is a genus of carnivorous dinosaur belonging to either the Allosauroidea or the Megalosauroidea known from the Late Jurassic of the US states Utah and Colorado. 
It was a medium sized theropod from known fossils, with specimens discovered so far suggesting a size range of 4.5-5.9 meters and 200-450 kg. The holotype ilium can be estimated at 44.2 centimeters when complete based on comparisons with its more complete relative Eustreptospondylus. More specimens are known, such as the paratypes which consist of more pelvic material.
Known skull material indicates Marshosaurus had a large skull for its size, with the largest discovered skulls being 60 cm long and the largest specimens possibly having skulls about 78.7 cm long. Its forelimbs were large, heavily-muscled, and massively built relative to its size, being tipped with especially large claws. The hindlimbs were also very robustly constructed as well as proportionally long, suggesting an animal evolved for both strength and speed to capture prey.
Marshosaurus lived alongside many more famous and larger dinosaur species, such as Allosaurus, Torvosaurus, Apatosaurus, Stegosaurus, and Camptosaurus.

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.

Bahariasaurus (meaning "Bahariya lizard") is a genus of theropod dinosaur found in the Bahariya Formation in Egypt, and the Farak Formation of Niger of North Africa, which date to the late Cretaceous Period, (Cenomanian age), about 95 million years ago. With the proportions of the likely close relatives Proceratosauridae and Megaraptora, it would have been 13-15 meters long and roughly 8000-10500 kg, placing it one of the largest land carnivores ever. Those sizes suggest the animal was much heavier than Tyrannosaurus rex and in the same size range as the contemporary gigantic theropods Carcharodontosaurus and Spinosaurus.
The type species, B. ingens, was described by Ernst Stromer in 1934, though Stromer's finds were destroyed during World War II. The exact placement of Bahariasaurus is uncertain with it having been variously assigned to several theropod groups, namely Ceratosauria, Megalosauroidea, Allosauroidea, and Tyrannosauroidea. Modern phylogenetic analyses favor the last option, recovering it both as a member of Megaraptora within the Tyrannosauroidea and as a non-megaraptoran basal tyrannosauroid. 
However, it has been postulated that not all of Stromer's material belonged to one taxon (explaining the phylogenetic instability) and that Bahariasaurus may have been the same animal as Deltadromeus, another giant basal tyrannosauroid from the same time and place. More specimens would be needed to more accurately classify it, and to determine its relationship to Deltadromeus. Researcher Mickey Mortimer believes Bahariasaurus is diagnostic, although this remains tentative for the time being.