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Posts Tagged ‘Carnivorans’

velvet claw

If you probably couldn’t tell from reading this blog, carnivoran evolution and natural history is one of my passions.

Where did all of this get started? I’d say sometime in the mid-90s. I used to watch A&E’s old Wildlife Mysteries series on Thursday nights. These were mostly very high quality wildlife documentaries and a lot of them were BBC productions.

Some of these films were shown in a series called “Carnivores.” It was about the evolution of the order Carnivora, minus the pinnipeds. And I loved it.

The series was based upon the work of David MacDonald, a carnivoran specialist and conservation biologist at Oxford.

In the UK, it was shown as “The Velvet Claw,” which is one reason I’ve had a few problems finding even clips of it online.

And for a long time, all that we could see are short clips, but now, well, it’s been uploaded in full.  Here is the entire series on Youtube.

I don’t know how long it’s going to be up, so you’d better watch it soon.

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A spotted hyena pseudo-penis. Source for image.

A spotted hyena pseudo-penis. Source for image.

I woke up this morning to check the comments on the blog. I normally do not close comments for older posts, and I often forget about the posts I wrote several years ago.

Some of them have never generated particularly good comments, and this particular one, which is not particularly profound or well-writen, is simply entitled Hyenas are not dogs. They are actually more closely related to cats.

The comments on there are pretty picayune and banal. The post was pretty picayune and banal, so what else would I expect?

Well, when I woke up this morning, I came across this gem, which I have to say is the worst creationist argument I’ve ever seen!

Here it is in all its glory:

Sorry, Hyenas are dogs. I do not care what you say. Evolution is a theory and has never been proven. Hyenas are not cats, and are not related to ferrets, weasels, civets, are any other animal. They are dogs plain and simple. If it looks like a duck and it quacks like a duck its a duck. Weasels, ferrets, civets, mongoose etc., do not look like dogs. Rest my case. Hyenas are dogs.

I hope this person is just acting a Poe.

It’s hard to tell with these creationists though. It really is.

I am having a hard time reading it without having blood vessels pop out.

First of all a ferret or a weasel is a Caniform Carnivoran. Caniforms are all closely related to dogs, though they are much closer in resemblance to primitive Caniformia than Canids (“the dog family”) are. The fact that they look like mongooses is really quite irrelevant.

Secondly, spotted hyenas look nothing like dogs, and only a really superficial examination of striped and brown hyenas would lead one to believe that they are anything like a dog. I know that the German and Afrikaans-speaking settlers to southern Africa called the brown hyena a “strandwolf.” The term means “beach wolf,” which is in reference to the ubiquity of brown hyenas along the Skeleton Coast, where they scavenge flotsam and jetsam and sometimes hunt fur seal pups. They were called wolves for the same reason that the same people called a giant antelope a moose. The eland antelope species of Africa are actually named after the Dutch/Afrikaans word for moose, which is eland. And it wasn’t just the eland antelope. Gemsbok, a type of oryx, share the same name with the chamois of Europe. Steenbok is the Dutch name for the Alpine Ibex. Rhebok are named for the Dutch/Afrikaans name for the European roe deer.  All of these animals antelope, but none of their European namesakes are.

They also called the spotted hyena the “tiger wolf.”

But people giving animals inappropriate common names is pretty common in just about every language. What we call a moose, the Europeans call an elk. What I call a robin is more closely relate to a European blackbird than to the European robin.

So ignore the names.

Let’s talk phylogeny.

Dogs and hyenas really don’t look that much like each other. All living species of hyenas, except the aardwolf (another misnamed “wolf”), have evolved a bone crushing capability in their jaws that no living dog has. However, in North America, there were once dogs that had this bone crushing capability. These dogs, called the Borophaginae (“bone crushers” or “bone eaters”) live between 36—2.5 million years ago in North America. Some of them were giants, and many were quite well-adapted eating the bones of megafauna.

No living dog is a true bone-eater. They will eat bones, but they will never crush them with efficiency of any species of hyena or one of those Borophagine dogs. (If you want to find out more about the evolution of bone crushing in Borophaginae and hyenas, check out this lecture at the Royal Tyrell Museum. It’s very fascinating.)

Then there is the DNA. We’ve been able to construct phylogenetic trees based upon genetic material. Every study that has examine Carnivoran DNA has placed hyenas with the Feliformia. They are most closely related to the true civets, which is the family Viverridae. They did evolve into something like a dog, and if you watch that lecture at the Royal Tyrell Museum, you’ll see that more primitive forms of hyena actually looked a lot more like dogs than modern ones do.

When phylogenetic trees are drawn from DNA samples, dogs fit with bears and seals (and the walrus and “eared seals”).

Hyenas and dogs are out of two entirely different lineages that split about 42 million years ago.

The fact that they superficially look alike is not evidence of a common designer at all.

The big difference between dogs and spotted hyenas in particular is their social structure. All dog societies, save domestic dogs and some red foxes, are base upon a mated pair in which there are no great size or phenotypical differences between males and females. In spotted hyena societies, the females are larger and have dominance over the males. Status is inherited from mother to daughter, which does not happen in any species of dog.

And one way the females maintain their dominance is through a fluke in their anatomy. Female spotted hyenas have genitalia that strongly resembles a male’s penis, but it’s actually the clitoris. And it’s through this tube that female spotted hyenas urinate, copulate, and give birth through this pseudo-penis. Female hyenas have absolute control over mating because they can move this “device” to prevent copulation. All a female dog can do is sit down with her tail between her legs and growl.

No dog species has this feature.

The only other mammal that has anything like this is the fossa of Madagascar. It is sort of a mongoose that became a cat. The females of this species are born with a pseudo-penis that becomes a “normal” clitoris as the animal mature.

Fossas were once thought to be civets, but like all Malagasy carnivorans, they are now believed to be more closely related to mongooses.

But it really doesn’t matter. Both mongooses and civets are Feliformia, as is the hyena.

And it does point to common ancestry, even if the rest of their relatives do not have this feature.

A spotted hyena is not a dog with a pseudo-penis.

This same argument if taken even further would lead one to believe that a thylacine was nothing more than a wolf with a pouch on it.

Thylacines looked a lot like wolves. (See this page at the Thylacine Museum to see how similar they were). Even trained anatomists have mistaken thylacine remains for those of wolves.

They actually looked much more like dogs than hyenas do.

And they are absolutely not related to dogs at all!

They are most closely related to either the quolls, which look like miniature arboreal thylacines, or to the numbat, which looks like a thylacine that evolved into an anteater. (It eats nothing but termites, but it has the anteater’s long tongue!)

These animals are all marsupials. They share no close ancestors with dogs or anteaters or cat or any placental mamals at all.

The split between placental and marsupial mammals is even more distant– at least 125 million years ago.

Why do they look the same?

Because natural selection required that these animals evolve similar bodies to fill somewhat similar niches. (Though it should be noted that thylacines actually did behave more like big cats than wolves.)

Believe it or not, this dog-like form has evolved several times in the past. Not only do we have the aforementioned dog-like hyenas and the thylacine, but there was once a crocodilian that looked very much like a hairless coyote.

By this creationists’ logic, all these animals would be called dogs.

And they aren’t at all!

Yes, I do know I used scientific terms for female genitalia, which I know creationists like are icky.

But seriously, how dumb can you be!

 

 

 

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From Richard Lydekker’s Royal Natural History: Mammals (1894) :

A large number of the mammals from the highlands of Tibet belong to types quite unlike those found in any other part of the world; and in no case is this dissimilarity more marked than in the animal which may be termed the particoloured bear (Aeluropus melanoleucus).

This strange animal, which has been known to European science only since the year 1869, is of the approximate dimensions of a small brown bear, and has a general bear-like aspect, although differing from all the other members of the family in its parti-coloured coat. The fur is long and close, with a thick, woolly under-fur. The general colour is white, but the eyes are surrounded with black rings, the small ears are also black, while the shoulders are marked by a transverse stripe of the same colour gradually increasing in width as it approaches the forelimbs, which are also entirely black, as are likewise the hind-limbs. This peculiar coloration communicates a most extraordinary appearance to the creature; and without knowing more of its natural surroundings it is difficult to imagine the object of such a staring contrast. The tail is extremely short; and the soles of the feet are hairy.

In addition to these external characteristics, the parti-coloured bear also presents some peculiar features in regard to the skull and teeth. Thus the skull is remarkable for the great width of the zygomatic arches and the enormous development of the longitudinal ridge on the upper-surface of the brain-case, both these features indicating greater power of jaw than has at present been found in anyother member of the entire carnivorous order. Then, again, the teeth differ both in number and form from those of all the other Ursidae. Instead of the forty-two teeth, characteristic of the typical bears, the parti-coloured bear has but forty teeth, all told; the diminution in number being due to the absence of the first pair of premolar teeth in the lower jaw. As regards form, the molar teeth are distinguished from those of other bears by their shorter and wider crowns; this being most marked in the first molar of the upper jaw, which is broader than it is long. The second upper molar tooth agrees, however, with the corresponding tooth of other bears in being longer than the one in front of it. The pattern formed by the tubercles on the crowns of these teeth is exceedingly complex, and approaches to that obtaining in the panda, among the raccoon family, to be noticed in the next chapter.

The parti-coloured bear is reported to inhabit the most inaccessible districts of Eastern Tibet, and to be of extremely rare occurrence. Unfortunately we are at present quite ignorant of its habits, although it is said to feed chiefly on roots and the young shoots of bamboos, and to be entirely herbivorous (pg. 32-33).

The animal described here is, of course, the giant panda. However, the range of the giant panda is not Tibet.  Their range is restricted to the Sichuan province of China, and another population can be found in the Qinling Mountains of the Shaanxi province.  Their range was originally more extensive, but their reliance of undisturbed thickets of bamboo and human hunting pressures meant that the only giant pandas left were in these remote regions.

The confusion with Tibet may come from the other panda– which is actually not a close relation.

The red panda or “firefox” (Ailurus fulgens) has been classified as a bear and as a raccoon. Currently, it is placed in its own family, Ailuridae. The two species both eat a lot of bamboo, but the red panda is not as specialized to living off of bamboo as the ursine giant panda. The two species have several morphological structures in common. Most notably, the two possess the “thumb” that is nothing more than an extension of the radial sesamoid bone.

Because of these similarities, the two were believed to be close relatives, but genomic analysis has found that the giant panda is a bear. Its fewer chromosomes were found to be fused bear chromosomes. And mitochondrial DNA analysis has found that the red panda is a unique species that is closely related to the raccoon family, the weasel family, and the skunk family– but it is such a unique lineage that it cannot be classified as belonging to any of these families.

Red pandas in recent centuries have been more widespread over the mountainous regions of Asia. Their range includes much of the Himalayas, including both Tibet and the Qinling Mountains, where a population of giant pandas can be found. But its range also extends south to Burma and includes both Indian and Nepal. IUCN considers it to be a threatened species. It is in no way as endangered as its supposed black and white cousin.

My guess is confusion with the red panda caused Lydekker to make the claim that these animals are Tibetan. Considering how little anyone knew about giant pandas at the time, it is a fair mistake.

Lydekker also didn’t know that the panda is one of the oldest bear species. It is most closely related the tremarctine bears– only one of which still exists, the South American spectacled bear (Tremarctos ornatus). The oldest giant panda fossil has been dated to 2.6 million year ago. However, this pygmy giant panda has been classified as a different species, though it was likely ancestral to the modern giant panda. ( “Pygmy giant panda” is quite the oxymoron, don’t you think?)

The giant panda is a truly unique species, but it shows the real dangers species can face if they become too specialized to a single niche and a single food source. If one’s fortune is hitched to only a very specific star, what happens if that star should burn out?

But this specialized animal has managed to survive 2.6 million years.

If only it could survive us.

 

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