Post by rock on Apr 24, 2019 16:40:45 GMT 5
hyaenodon gigas
Although Hyaenodon translates as ‘hyena tooth’ the only similarities between Hyaenodon and hyenas are the facts that they are both mammals and they both eat meat. Beyond this they are completely different animals with hyenas being more closely related to cats and Hyaenodon actually being a creodont, a long extinct group of mammals that did not survive the Miocene.
Hyaenodon was the top predator of its day with the larger forms dominating the landscapes throughout the Oligocene periods. Key to this success was the large head that compared to today’s animals looks too large to fit upon the body. Indeed the neural spines of the forward dorsal vertebrae are enlarged to allow for an increased surface are for the attachment of neck muscles powerful enough to support the enlarged skull.
The skull itself has attachments that allow for the fixing of immensely powerful biting muscles would enable the jaws to easily crush prey animals in its mouth. Usually this would involve Hyaenodon biting the head or neck area of the animal. Evidence for this comes from a comparison of predator skulls with the skull of a nimravid called Dinictis which has puncture holes in its cranium that closely match the tooth pattern of Hyaenodon. Additionally coprolites which have been interpreted to belonging to Hyaenodon also have fragmentary parts of other animal skulls in them.
Hyaenodon did not rely upon just crushing animals in its jaws however. Once the prey was down it had to be eaten and for this Hyaenodon had specially adapted slicing teeth at the back of these jaws. The really interesting thing about these teeth is that as the animal grew older these slicing teeth would rotate against each other. This constant grinding against each other meant that Hyaenodon maintained a cutting edge across these teeth for much longer than other carnivores and possibly had a longer life expectancy because of it. This also allowed Hyaenodon to slice meat into smaller pieces rather than gulping down large chunks, something that would allow for faster and more efficient digestion. This is very simply explained by the fact that smaller pieces would result in a larger surface area exposed to the digestive acids in the stomach than would happen if it were a single large piece. A modern analogy would be chemists placing a solid into a solution will almost always use a powdered form of that solid for this very reason.
The slicing teeth that did most of the work in eating where placed at the back of the mouth where they were closer to the point of jaw articulation. This is actually a very common area for the placement of the actual eating teeth because it places them nearer the fulcrum of the jaw mechanism that allows for far more force to be focused through these teeth. This is also why the teeth in the front of your mouth are shaper for biting off a piece of food, while the flatter molar teeth that you use to actually chew your food at nearer the back.
Spending more time processing food in the mouth meant that Hyaenodon would not have been able to breathe through its mouth while it was full with whatever it had just killed. But Hyaenodon had a very simple adaptation to deal with this and this was a bony palate that extended well beyond the back teeth of the upper jaw. This supported the nasal passages so that they continued to carry air to and from the lungs even when the mouth was otherwise blocked.
Out of all its senses, smell seems to have been the most important to Hyaenodon due to CAT scans that reveal a well-developed olfactory bulb. Include the larger skull that would have meant a nasal area with a proportionally larger surface area than a smaller skulled animal, and its reasonable that Hyaenodon tracked prey by scent, possibly identifying which animals were sicker and weaker than the others.
However there is fossil evidence that Hyaenodon did not just randomly roam across the countryside hoping to pick up a scent. A fossil site of what was once a watering hole has been found that contains large numbers of herbivore as well as Hyaenodon remains. While this could be interpreted as Hyaenodon just drinking, predators in other parts of the World such as Africa have been observed to frequent watering holes while hunting for prey. This is simple but also very intelligent behaviour as it is pointless to expend energy on the chance of maybe finding prey some distance from a watering hole, when by staying put you know that your prey will have to eventually come to you in order for the chance to drink.
By being in those locations Hyaenodon would have waited for its target to settle down and drink. With its guard down, Hyaenodon could ambush it from the undergrowth and be upon its prey before it had time to react, with the crushing jaws clamping around its preys head to bring a swift kill. Further fossil evidence for a variety of other animals from small oreodonts, rhinos, camels to even primitive horses like Mesohippus show signs of being fed upon by Hyaenodon which suggests that this predator was not especially selective about what it hunted.
Like with so many of the Cenozoic predators, Hyaenodon seems to have succumbed to the effects of climate change rather than a specific extinction event. As the Miocene period progressed the world’s climate became drier due to global cooling that also resulted in a reduction of sea levels. The result on land was that forests and scrub were being replaced by vast expanses of grassland that many of the herbivores such as the oreodonts were not suited to eating, meaning that the oreodonts that were one of the more common animals disappeared from the menu. Additionally other herbivorous animals were beginning to grow larger with longer legs so that they could better cope with this new kind of environment. As such the types of animals that Hyaenodon used to prey upon like the horses and the camels were becoming too fast for Hyaenodon to catch, with greatly reduced amounts of cover denying Hyaenodon the chance to use ambush tactics to sneak up on prey.
The final occurrence that completed the demise of Hyaenodon was the emergence of new carnivores such as the bear dogs, and while they are more often associated with the old world (such as Asia, Europe, Africa), they were able to spread into North America by crossing the Bering land bridge that was created by the aforementioned falling sea levels. The most famous of this group is Amphicyon, but all of these new predators were more suited to hunting across open ground as well as having larger and more powerful bodies. Hyaenodon could not compete with these new hunters and was quickly relegated to a subordinate position to them. No longer being able to kill its own food, or even scavenge the kills of the more powerful bear dogs, meant that by this stage Hyaenodon was living upon borrowed time.
african lion
Living in the grasslands, scrub, and open woodlands of sub-Saharan Africa, the lion is the second largest cat in the world. It is dwarfed slightly by the tiger, which is closely related and has a very similar body type.
Unlike other cats, lions are very social animals. They live in groups, called prides, of around 30 lions. A pride consists of up to three males, a dozen related females, and their young. The size of the pride is determined by the availability of food and water. If resources are scarce, the pride becomes smaller.
Pride members keep track of one another by roaring. Both males and females have a very powerful roar that can be heard up to 8 km (5 mi.) away.
Males and females take on very different roles in the pride. Male lions spend their time guarding their territory and their cubs. They maintain the boundaries of their territory, which can be as large as 260 sq. km (100 sq. mi.), by roaring, marking it with urine, and chasing off intruders. Their thick manes, a unique trait to male lions, protect their necks when they fight with challengers.
Big male lionFemale lions are the primary hunters of the group. They are smaller and more agile than males. But since their prey is still generally faster than them, they use teamwork to bring an animal down. Fanning out, they form a semicircle, with the smaller, weaker lionesses herding the prey towards the center. Then the stronger females knock the animal down and make the kill.
Lions usually hunt at night. Their prey includes antelopes, buffaloes, zebras, young elephants, rhinos, hippos, wild hogs, crocodiles and giraffes. But they also sometimes eat smaller prey like mice, birds, hares, lizards, and tortoises. They are not above stealing kills from other carnivores, like hyenas, wild dogs, cheetahs, and leopards, or scavenging spoiled meat.
After a successful hunt, all the lions in the pride share the meal. But there is a pecking order, with the adult males taking first claim, followed by the lionesses, and finally, the cubs.
Lions have a fast-working digestive system, which allows them to gorge themselves and then go for seconds shortly after. If available, they will drink water everyday. But they can go 4-5 days without drinking by obtaining moisture from the stomach contents of their prey.
Spending 16-20 hours of the day sleeping or resting, lions are the laziest of the big cats. They can be found lying on their backs with their feet up or taking a snooze up in a tree. While lazing around, they are very affectionate towards one another, rubbing heads, grooming, and purring.
Lionesses give birth to 2-3 cubs at a time. Usually a couple females give birth around the same time. The cubs are then raised together, sometimes nursing communally.
Lioness with cubsVulnerable to predators like hyenas, leopards, and black-backed jackals, cubs have a 60-70% mortality rate. They are sometimes trampled by large animals like buffaloes. Furthermore, when another group of male lions takes over a pride, they kill all the cubs so they can sire their own with the lionesses.
Female cubs stay with the group as they age. At around two years old, they become capable hunters. But young males are forced out of the pride at that age. They form bachelor groups and follow migrating herds until they are strong enough to challenge male lions of other prides. In general, a group of males stays in power in the pride for around three years before another bachelor group takes it over.
Although Hyaenodon translates as ‘hyena tooth’ the only similarities between Hyaenodon and hyenas are the facts that they are both mammals and they both eat meat. Beyond this they are completely different animals with hyenas being more closely related to cats and Hyaenodon actually being a creodont, a long extinct group of mammals that did not survive the Miocene.
Hyaenodon was the top predator of its day with the larger forms dominating the landscapes throughout the Oligocene periods. Key to this success was the large head that compared to today’s animals looks too large to fit upon the body. Indeed the neural spines of the forward dorsal vertebrae are enlarged to allow for an increased surface are for the attachment of neck muscles powerful enough to support the enlarged skull.
The skull itself has attachments that allow for the fixing of immensely powerful biting muscles would enable the jaws to easily crush prey animals in its mouth. Usually this would involve Hyaenodon biting the head or neck area of the animal. Evidence for this comes from a comparison of predator skulls with the skull of a nimravid called Dinictis which has puncture holes in its cranium that closely match the tooth pattern of Hyaenodon. Additionally coprolites which have been interpreted to belonging to Hyaenodon also have fragmentary parts of other animal skulls in them.
Hyaenodon did not rely upon just crushing animals in its jaws however. Once the prey was down it had to be eaten and for this Hyaenodon had specially adapted slicing teeth at the back of these jaws. The really interesting thing about these teeth is that as the animal grew older these slicing teeth would rotate against each other. This constant grinding against each other meant that Hyaenodon maintained a cutting edge across these teeth for much longer than other carnivores and possibly had a longer life expectancy because of it. This also allowed Hyaenodon to slice meat into smaller pieces rather than gulping down large chunks, something that would allow for faster and more efficient digestion. This is very simply explained by the fact that smaller pieces would result in a larger surface area exposed to the digestive acids in the stomach than would happen if it were a single large piece. A modern analogy would be chemists placing a solid into a solution will almost always use a powdered form of that solid for this very reason.
The slicing teeth that did most of the work in eating where placed at the back of the mouth where they were closer to the point of jaw articulation. This is actually a very common area for the placement of the actual eating teeth because it places them nearer the fulcrum of the jaw mechanism that allows for far more force to be focused through these teeth. This is also why the teeth in the front of your mouth are shaper for biting off a piece of food, while the flatter molar teeth that you use to actually chew your food at nearer the back.
Spending more time processing food in the mouth meant that Hyaenodon would not have been able to breathe through its mouth while it was full with whatever it had just killed. But Hyaenodon had a very simple adaptation to deal with this and this was a bony palate that extended well beyond the back teeth of the upper jaw. This supported the nasal passages so that they continued to carry air to and from the lungs even when the mouth was otherwise blocked.
Out of all its senses, smell seems to have been the most important to Hyaenodon due to CAT scans that reveal a well-developed olfactory bulb. Include the larger skull that would have meant a nasal area with a proportionally larger surface area than a smaller skulled animal, and its reasonable that Hyaenodon tracked prey by scent, possibly identifying which animals were sicker and weaker than the others.
However there is fossil evidence that Hyaenodon did not just randomly roam across the countryside hoping to pick up a scent. A fossil site of what was once a watering hole has been found that contains large numbers of herbivore as well as Hyaenodon remains. While this could be interpreted as Hyaenodon just drinking, predators in other parts of the World such as Africa have been observed to frequent watering holes while hunting for prey. This is simple but also very intelligent behaviour as it is pointless to expend energy on the chance of maybe finding prey some distance from a watering hole, when by staying put you know that your prey will have to eventually come to you in order for the chance to drink.
By being in those locations Hyaenodon would have waited for its target to settle down and drink. With its guard down, Hyaenodon could ambush it from the undergrowth and be upon its prey before it had time to react, with the crushing jaws clamping around its preys head to bring a swift kill. Further fossil evidence for a variety of other animals from small oreodonts, rhinos, camels to even primitive horses like Mesohippus show signs of being fed upon by Hyaenodon which suggests that this predator was not especially selective about what it hunted.
Like with so many of the Cenozoic predators, Hyaenodon seems to have succumbed to the effects of climate change rather than a specific extinction event. As the Miocene period progressed the world’s climate became drier due to global cooling that also resulted in a reduction of sea levels. The result on land was that forests and scrub were being replaced by vast expanses of grassland that many of the herbivores such as the oreodonts were not suited to eating, meaning that the oreodonts that were one of the more common animals disappeared from the menu. Additionally other herbivorous animals were beginning to grow larger with longer legs so that they could better cope with this new kind of environment. As such the types of animals that Hyaenodon used to prey upon like the horses and the camels were becoming too fast for Hyaenodon to catch, with greatly reduced amounts of cover denying Hyaenodon the chance to use ambush tactics to sneak up on prey.
The final occurrence that completed the demise of Hyaenodon was the emergence of new carnivores such as the bear dogs, and while they are more often associated with the old world (such as Asia, Europe, Africa), they were able to spread into North America by crossing the Bering land bridge that was created by the aforementioned falling sea levels. The most famous of this group is Amphicyon, but all of these new predators were more suited to hunting across open ground as well as having larger and more powerful bodies. Hyaenodon could not compete with these new hunters and was quickly relegated to a subordinate position to them. No longer being able to kill its own food, or even scavenge the kills of the more powerful bear dogs, meant that by this stage Hyaenodon was living upon borrowed time.
african lion
Living in the grasslands, scrub, and open woodlands of sub-Saharan Africa, the lion is the second largest cat in the world. It is dwarfed slightly by the tiger, which is closely related and has a very similar body type.
Unlike other cats, lions are very social animals. They live in groups, called prides, of around 30 lions. A pride consists of up to three males, a dozen related females, and their young. The size of the pride is determined by the availability of food and water. If resources are scarce, the pride becomes smaller.
Pride members keep track of one another by roaring. Both males and females have a very powerful roar that can be heard up to 8 km (5 mi.) away.
Males and females take on very different roles in the pride. Male lions spend their time guarding their territory and their cubs. They maintain the boundaries of their territory, which can be as large as 260 sq. km (100 sq. mi.), by roaring, marking it with urine, and chasing off intruders. Their thick manes, a unique trait to male lions, protect their necks when they fight with challengers.
Big male lionFemale lions are the primary hunters of the group. They are smaller and more agile than males. But since their prey is still generally faster than them, they use teamwork to bring an animal down. Fanning out, they form a semicircle, with the smaller, weaker lionesses herding the prey towards the center. Then the stronger females knock the animal down and make the kill.
Lions usually hunt at night. Their prey includes antelopes, buffaloes, zebras, young elephants, rhinos, hippos, wild hogs, crocodiles and giraffes. But they also sometimes eat smaller prey like mice, birds, hares, lizards, and tortoises. They are not above stealing kills from other carnivores, like hyenas, wild dogs, cheetahs, and leopards, or scavenging spoiled meat.
After a successful hunt, all the lions in the pride share the meal. But there is a pecking order, with the adult males taking first claim, followed by the lionesses, and finally, the cubs.
Lions have a fast-working digestive system, which allows them to gorge themselves and then go for seconds shortly after. If available, they will drink water everyday. But they can go 4-5 days without drinking by obtaining moisture from the stomach contents of their prey.
Spending 16-20 hours of the day sleeping or resting, lions are the laziest of the big cats. They can be found lying on their backs with their feet up or taking a snooze up in a tree. While lazing around, they are very affectionate towards one another, rubbing heads, grooming, and purring.
Lionesses give birth to 2-3 cubs at a time. Usually a couple females give birth around the same time. The cubs are then raised together, sometimes nursing communally.
Lioness with cubsVulnerable to predators like hyenas, leopards, and black-backed jackals, cubs have a 60-70% mortality rate. They are sometimes trampled by large animals like buffaloes. Furthermore, when another group of male lions takes over a pride, they kill all the cubs so they can sire their own with the lionesses.
Female cubs stay with the group as they age. At around two years old, they become capable hunters. But young males are forced out of the pride at that age. They form bachelor groups and follow migrating herds until they are strong enough to challenge male lions of other prides. In general, a group of males stays in power in the pride for around three years before another bachelor group takes it over.
