Note: I will be quoting a thread from Dinosaur Home quite often in this post, so here’s the link to it:http://www.dinosaurhome.com/a-simple-question-on-t-rex.-based-on-fossil-evidence.-has-an…-128402.html#17621
To begin, I’d like to indicate that in the above thread, the possibility of large Late Cretaceous theropods hunting sauropods has been brought up by a couple people. Now I’d like to quote tzavecz, who is one of the many people discussing this fascinating topic (All quotes I make are from the above link).
“There a paper less than six years old on a Titanosaurid from Northen Mexico that was about the same time frame. [85 million years ago]”
I think what tzavecz is referring to here is the Alamosaurus, which was a large sauropod that lived in New Mexico during the Late Cretaceous.
http://en.wikipedia.org/wiki/Alamosaurus
*Note: I know that some people believe Wikipedia to be unreliable, so I think it’s worth mentioning that I’m only using it to validate the existence of Alamosaurus, not to state any facts about it.
Though not a Late Jurassic sauropod, Alamosaurus was very large, probably reaching lengths near to or exceeding the lengths of the Jurassic Giants. The beast probably lived in large herds as most other herbivorous dinosaurs (especially sauropods) did. Now, during the Late Jurassic, theropods such as Allosaurus would often hunt in packs to take down a weak, old, young, or sick sauropod; they would do this by separating the animal from the rest of the herd, then moving in for the kill. And the kill would feed all individuals for a decent period of time.
In the case of Alamosaurus, one large predator lived alongside it, one of the most notorious dinosaurs known: Tyrannosaurus rex. T. rex specimens have been found as far north as Canada and as far south as New Mexico, so my guess is that these two creatures (Alamosaurus and Tyrannosaurus) did often encounter each other physically from time to time. And it is entirely possible that, on occasion, rexes would get together to hunt an individual Alamosaurus just as the Allosaurus did millions of years before them.
But the link stops there. To my knowledge, no large sauropods dating back to the Late Cretaceous have been found north of New Mexico (somebody correct me if I’m wrong here…). Now I’d like to quote HitBear:
“They’d have to take down a lot more prey to feed such a large group, and the hit / miss ratio for preditors has always been very high in favour of misses.”
The largest dinosaurs available to the majority of large predators during the Late Cretaceous were the hadrosaurs, commonly referred to as the “duckbill dinosaurs” for their characteristic mouth that resembles a duck’s bill.
Backing up for a second, it was also mentioned in the thread that Barnum Brown discovered 22 individual Albertosaurus in the same location. Brown’s find included one old individual, eight adults, seven sub-adults, and six juveniles. This find was unlike the La Brea tar pits in California and the Cleveland-Lloyd Dinosaur Quarry in Utah; there was no particular reason for these individuals to be together, other than (allegedly) the possibility that they were a pack of Albertosaurus. We’ll refer to this discovery often in the rest of this post, so bear that in mind. (to learn more about this find, visit http://www.nceas.ucsb.edu/jai/podcast_publications/inouye_science_dinosaur.pdf)
Going back to the hadrosaurs and relating it to the group of 22 Albertosaurus, it would take a lot of time and effort to kill enough hadrosaurs to feed such a large group. Theoretically, it is possible; realistically, it’s unlikely. As HitBear said, the hit/miss ratio is simply too high and the food supply is simply too low.
But there’s still the matter of why those 22 Albertosaurus were found together. Some scientists say that external factors such as floods or fires brought them together. But why were no other dinosaurs or animals found at the site; why only the Albertosaurus? Surely if a natural disaster were the explanation, other animals would be present? Whatever the reason for their being together is, it’s a potential piece to the puzzle of the predatory behavior of large Late Cretaceous theropods.
What of the matter of even larger theropods, such as Tyrannosaurus? It’d take even more time and effort to kill enough hadrosaurs to feed a large T. rex pack, especially if it consisted of 22 individuals as did the Albertosaurus discovery. Theoretically, rexes in New Mexico could work together in packs to take down Alamosaurus, but what of the other areas, where there were no extremely large herbivores that T. rex could prey upon? Loops right back to the hadrosaur issue, doesn’t it?
I’m not saying that it was impossible for large Late Cretaceous theropods to successfully live in large packs, nor am I saying that they definitely did it. I’m simply stating the facts and my personal opinions/theories on these facts. Personally, I believe there’s validity to both sides of this debate, and I find it difficult to pick a side. Based on the data I’ve seen, my personal conclusion is that, although it is possible that these large Late Cretaceous theropods hunted in packs, it is highly unlikely that they did so on a regular basis.
I hope this post was educational and helpful. If there’s anything I missed, or if you have any questions/comments you’d like to make, feel free to leave a comment below.
Friday, June 15, 2012
Sunday, December 19, 2010
Utahraptor Research, Part 6: Sexual Dimorphism
This is a bonus post. This was not originally posted on dinosaurhome.com, where I frequent.
Sexual dimorphism is the differences between a male and a female of the same species. Dimorphism comes from two Greek words: di meaning two and morph meaning form. In mallards, for example, the male has a green head and a more brilliant body than the female. In most species of spiders, the female is much larger than the male. This might have been the case for dinosaurs, as well. For example, a female Tyrannosaurus was slightly larger than a male Tyrannosaurus. In the case of Utahraptor, the female might have been a little larger than the male.
Sexual dimorphism is the differences between a male and a female of the same species. Dimorphism comes from two Greek words: di meaning two and morph meaning form. In mallards, for example, the male has a green head and a more brilliant body than the female. In most species of spiders, the female is much larger than the male. This might have been the case for dinosaurs, as well. For example, a female Tyrannosaurus was slightly larger than a male Tyrannosaurus. In the case of Utahraptor, the female might have been a little larger than the male.
Saturday, November 13, 2010
Utahraptor Research, Part 5: Questions and Habitat
Questions
Q: Was Utahraptor warm-blooded or cold-blooded?
A: This is one of the toughest questions asked by paleontologists; were dinosaurs warm-blooded or cold-blooded? In retrospect, I think they were both warm and cold-blooded. Predators like Allosaurus had to be warm-blooded so they could catch their prey in the early morning, which is when they usually liked to hunt. Now, in the case of Utahraptor and other dromaeosaurs, I think they were warm-blooded because they could run fairly quickly. Plus, they might have been nocturnal, which means they hunted at night. Night was the coldest time, and its prey was probably not very fast at night.
Q: How did Utahraptor die out?
A: Utahraptor probably died because of the changing environment. You have to remember; it lived in the early Cretaceous. Earth was cooling down. Utahraptor had probably been adapted to a warmer and drier climate. Once the climate became somewhat cooler and wetter, this caused Utahraptors everywhere to die.
Q: How old did Utahraptor get before it died?
A: That’s a very good question. I’m not entirely sure, but I think it could probably be up to 65-70 years old, based on modern-day life spans of creatures it is related to.
Q: How long did Utahraptor live before they became extinct?
A: Utahraptor lived about 5 million years before they became extinct.
Habitat
Utahraptor packs probably lived in forests or deserts/prairies where hunting wouldn’t be a problem. They probably had a certain amount of territory, probably up to 3 miles in all directions, and part of their territory could have been near a water source, such as a lake, river, or stream. This suggests, but does not prove, that Utahraptor ate fish as part of its regular diet. The following descriptions are of the habitats of Utahraptor.
Forest
In the forest, Utahraptor would probably have hunted rodent-like creatures and lizards. The forest is probably where they would put their nests. Utahraptor packs guarded their nests very well. They would leave one or two guards behind while the rest of the pack hunts. Then, they would probably bring back some leftovers for the guards. Forest Utahraptors would have been rare, since at that time, the landscape was mostly barren desert, with very few forests.
Deserts/Prairies
The desert/prairie was probably where Utahraptor did most of its hunting when it comes to big game. They would try to separate a young or weak creature from the rest of its herd, then they would kill the separated creature. Often, the prey animal wouldn’t be enough to supply all Utahraptor with food. Therefore, there were probably feeding frenzies, in which some of the members of the pack may have been injured or killed.
Q: Was Utahraptor warm-blooded or cold-blooded?
A: This is one of the toughest questions asked by paleontologists; were dinosaurs warm-blooded or cold-blooded? In retrospect, I think they were both warm and cold-blooded. Predators like Allosaurus had to be warm-blooded so they could catch their prey in the early morning, which is when they usually liked to hunt. Now, in the case of Utahraptor and other dromaeosaurs, I think they were warm-blooded because they could run fairly quickly. Plus, they might have been nocturnal, which means they hunted at night. Night was the coldest time, and its prey was probably not very fast at night.
Q: How did Utahraptor die out?
A: Utahraptor probably died because of the changing environment. You have to remember; it lived in the early Cretaceous. Earth was cooling down. Utahraptor had probably been adapted to a warmer and drier climate. Once the climate became somewhat cooler and wetter, this caused Utahraptors everywhere to die.
Q: How old did Utahraptor get before it died?
A: That’s a very good question. I’m not entirely sure, but I think it could probably be up to 65-70 years old, based on modern-day life spans of creatures it is related to.
Q: How long did Utahraptor live before they became extinct?
A: Utahraptor lived about 5 million years before they became extinct.
Habitat
Utahraptor packs probably lived in forests or deserts/prairies where hunting wouldn’t be a problem. They probably had a certain amount of territory, probably up to 3 miles in all directions, and part of their territory could have been near a water source, such as a lake, river, or stream. This suggests, but does not prove, that Utahraptor ate fish as part of its regular diet. The following descriptions are of the habitats of Utahraptor.
Forest
In the forest, Utahraptor would probably have hunted rodent-like creatures and lizards. The forest is probably where they would put their nests. Utahraptor packs guarded their nests very well. They would leave one or two guards behind while the rest of the pack hunts. Then, they would probably bring back some leftovers for the guards. Forest Utahraptors would have been rare, since at that time, the landscape was mostly barren desert, with very few forests.
Deserts/Prairies
The desert/prairie was probably where Utahraptor did most of its hunting when it comes to big game. They would try to separate a young or weak creature from the rest of its herd, then they would kill the separated creature. Often, the prey animal wouldn’t be enough to supply all Utahraptor with food. Therefore, there were probably feeding frenzies, in which some of the members of the pack may have been injured or killed.
Wednesday, May 12, 2010
Utahraptor Research, Part 4: Diet, Speed and Agility
Diet
Utahraptor’s diet wasn’t very complicated. They would hunt anything that was available to them. When it comes to water, Utahraptor probably didn't need to drink a whole lot, since it probably got most of its water from the blood of its prey. However, due to the fact it mostly lived in a semi-arid climate, it probably still had to drink fresh water. It is possible that Utahraptor scavenged when it couldn’t find anything else to eat. Since it was one of the largest carnivores of the early Cretaceous, it could probably scare most other predators away from a carcass that it wanted to feed on. But scavenged meat was a last resort for Utahraptor, because this large dromaeosaur was designed for speed and agility, although it was more of an ambush predator, rather than a head-on battler.
Speed and agility
Utahraptor was agile, and could probably outrun most other dinosaurs during its time. However, it was more of a heavyweight fighter, rather than a more agile Velociraptor, which relied on its ferocity and dexterity, rather than its size. Utahraptor was the fastest carnivore in the early Cretaceous, although it could only run fast in short, quick bursts of speed. At top speed, Utahraptor could probably run up to 20 miles per hour for about 5-10 seconds. It wasn’t any faster because of its size. (However, the typical dromaeosaur [3 ft. tall, 6 ft. long] could reach speeds up to 25-30 miles per hour.) Dromaeosaurs could run so fast because a.) Their legs were very strong and b.) because of their lung design. First, the raptor would, obviously, inhale air. Then, that air would travel to various bones and vertebrae as well as the lungs. Finally, the remaining air exited the body through holes in various bones and escaped through the animal's pores in its skin. This method conserved energy because the raptor didn't have to let as much air out of its lungs.
Utahraptor’s diet wasn’t very complicated. They would hunt anything that was available to them. When it comes to water, Utahraptor probably didn't need to drink a whole lot, since it probably got most of its water from the blood of its prey. However, due to the fact it mostly lived in a semi-arid climate, it probably still had to drink fresh water. It is possible that Utahraptor scavenged when it couldn’t find anything else to eat. Since it was one of the largest carnivores of the early Cretaceous, it could probably scare most other predators away from a carcass that it wanted to feed on. But scavenged meat was a last resort for Utahraptor, because this large dromaeosaur was designed for speed and agility, although it was more of an ambush predator, rather than a head-on battler.
Speed and agility
Utahraptor was agile, and could probably outrun most other dinosaurs during its time. However, it was more of a heavyweight fighter, rather than a more agile Velociraptor, which relied on its ferocity and dexterity, rather than its size. Utahraptor was the fastest carnivore in the early Cretaceous, although it could only run fast in short, quick bursts of speed. At top speed, Utahraptor could probably run up to 20 miles per hour for about 5-10 seconds. It wasn’t any faster because of its size. (However, the typical dromaeosaur [3 ft. tall, 6 ft. long] could reach speeds up to 25-30 miles per hour.) Dromaeosaurs could run so fast because a.) Their legs were very strong and b.) because of their lung design. First, the raptor would, obviously, inhale air. Then, that air would travel to various bones and vertebrae as well as the lungs. Finally, the remaining air exited the body through holes in various bones and escaped through the animal's pores in its skin. This method conserved energy because the raptor didn't have to let as much air out of its lungs.
Saturday, March 6, 2010
Utahraptor Research, Part 3: Weapons and how it used them during mating season
Weapons
Utahraptor had many extremely dangerous weapons to use in combat. Its first weapon was its brain. Utahraptor was a master strategist, and had a fairly expanded brain. Its second weapon it had were the claws on its hands. It used the claws to slash and rip apart its prey, and also to get to the good stuff once the prey animal had died. Its third combat weapon was its second toe, which was the deadly toe claw. Utahraptor would use its toe claw to stab its prey, possibly in the jugular vein or spine, causing paralysis and/or death. Its teeth in its jaws were also a crucial weapon, used to tear apart and eat a carcass. Its next weapon was crucial in the hunting process. Utahraptor’s tail was used for balance when it was bringing down a prey animal, and also when the animal was running.
How it used these weapons during mating season
During the mating season, Utahraptor males would probably become more aggressive towards each other. During the fight to find a female, however, the males were probably careful not to hurt each other. They might've grab onto each other’s shoulders and had a shoving match. Whoever fell to the ground first would be the loser, and he wouldn’t win the right to mate. Of course, sometimes they would snap at each other, but rarely would any of the males be seriously injured. In the case of two females in the group, the best two males would get to choose a female. Sometimes, a certain male could become unlucky all through its life. The shoving matches they had may not have always been safe. If the male who lost the match wasn’t happy, it may have gotten into a screeching match with the winner. And in some of these cases, the winner may challenge the loser to a real fight; one that has all the dangers; a fight to the death. Here is what a fight to the death may have looked like:
The losing Utahraptor and the winning Utahraptor are circling each other slowly. They are snarling and hissing at each other, trying to get the other to back down before things got ugly. But neither of them are backing down. Their pride as a Utahraptor is on the line if nobody backs down. At first, it looks as if the Utahraptor that isn’t going to mate is backing down. But then, he rams the other Utahraptor right in the stomach. The raptor falls to the ground, surprised. The winner then leaps to his feet and tackles the other Utahraptor. They start to roll in the dirt, clawing and biting at each other. Suddenly, there is a loud shriek of pain. The Utahraptor that had the right to mate has just stuck his toe claw in the other Utahraptor’s stomach! The victor decides to gloat by roaring loudly.
Utahraptor had many extremely dangerous weapons to use in combat. Its first weapon was its brain. Utahraptor was a master strategist, and had a fairly expanded brain. Its second weapon it had were the claws on its hands. It used the claws to slash and rip apart its prey, and also to get to the good stuff once the prey animal had died. Its third combat weapon was its second toe, which was the deadly toe claw. Utahraptor would use its toe claw to stab its prey, possibly in the jugular vein or spine, causing paralysis and/or death. Its teeth in its jaws were also a crucial weapon, used to tear apart and eat a carcass. Its next weapon was crucial in the hunting process. Utahraptor’s tail was used for balance when it was bringing down a prey animal, and also when the animal was running.
How it used these weapons during mating season
During the mating season, Utahraptor males would probably become more aggressive towards each other. During the fight to find a female, however, the males were probably careful not to hurt each other. They might've grab onto each other’s shoulders and had a shoving match. Whoever fell to the ground first would be the loser, and he wouldn’t win the right to mate. Of course, sometimes they would snap at each other, but rarely would any of the males be seriously injured. In the case of two females in the group, the best two males would get to choose a female. Sometimes, a certain male could become unlucky all through its life. The shoving matches they had may not have always been safe. If the male who lost the match wasn’t happy, it may have gotten into a screeching match with the winner. And in some of these cases, the winner may challenge the loser to a real fight; one that has all the dangers; a fight to the death. Here is what a fight to the death may have looked like:
The losing Utahraptor and the winning Utahraptor are circling each other slowly. They are snarling and hissing at each other, trying to get the other to back down before things got ugly. But neither of them are backing down. Their pride as a Utahraptor is on the line if nobody backs down. At first, it looks as if the Utahraptor that isn’t going to mate is backing down. But then, he rams the other Utahraptor right in the stomach. The raptor falls to the ground, surprised. The winner then leaps to his feet and tackles the other Utahraptor. They start to roll in the dirt, clawing and biting at each other. Suddenly, there is a loud shriek of pain. The Utahraptor that had the right to mate has just stuck his toe claw in the other Utahraptor’s stomach! The victor decides to gloat by roaring loudly.
Wednesday, February 24, 2010
Fossil photos
A 50 million year old shark tooth.
Fossil dung, a.k.a. coprolite.
A fossil leaf.
Some fossil fish from Green River, Wyoming.
Saturday, February 20, 2010
Dinosaur web show coming soon
I have decided to create and publish a dinosaur web show every two weeks. These web shows will contain information about certain families of dinosaurs (for example, the first show will focus on dromaeosaurs). There will always be a part one and a part two of the web show, so I will discuss approximately twelve dinosaur families per year. I will try to get these web shows up as soon as they are finished.
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