Monthly Archives: December 2016

Sprint of the giant cheetah

Today the cheetah, Acinonyx jubatus is the only cat with clear adaptations for extremely fast sprint running, but in the past there were other species, more or less closely related to it, which also developed that kind of specialisation. The American cats of the genus Miracinonyx (about which I wrote in some detail in an earlier post) lived during the Pleistocene and paralleled to a remarkable degree the cursorial features of the cheetah skeleton, although none of them was quite as specialised as the true cheetah. But in the Pliocene and Pleistocene of the Old World there was an early species of the true cheetah genus Acinonyx, what we could call a cheetah with a difference. Of course I am talking about Acinonyx pardinensis, the giant cheetah known from many fossil sites from Spain to China, and which is known to have been considerably taller than the modern species. It is tempting to imagine that, having comparable adaptations for running as the modern cheetah but with absolutely longer limbs, the giant cheetah could have reached higher peak speeds, but would it?
Many years ago I had the opportunity to study casts of a partial skeleton of A. pardinensis from Perrier (France) housed at the Paris Museum of Natural History, and I was impressed by the animal’s enormous size and advanced running adaptations. The animal probably weighted about 70 kg, but its limb bones were quite elongated and so were its lumbar vertebrae, betraying a long and flexible back just as in the modern cheetah. But a detailed examination reveals some features in which the giant cheetah appears to be intermediate between the advanced morphology of the modern cheetah and that of the more “normal”, slower cats. For instance, the femur is not as strongly bowed as in A. jubatus, and the fibula is relatively robust without signs of the incipient fusion with the tibia observed in living cheetahs. In the radius, the tuber for the biceps muscle occupies about 10% of the shaft length in A. pardinensis as in most felines, while in the modern cheetah it is only half that long (muscle force tends to concentrate in the proximal part of the limb in the cheetah, as in all cursorial mammals).

Here are some of the limb bones of A. pardinensis that I photographed in Paris
a-pardinensis-limb-bones-paris

And here are some of the animal’s vertebrae
a-pardinensis-vertebrae-paris

In this comparative drawing the skeleton of the modern cheetah, Acinonyx jubatus (foreground) is shown to the same scale as the extinct giant cheetah, Acinonyx pardinensis (background)
a-pardinensis-skel-to-scale-with-a-jubatus

More recently, the bones of the forelimb of a giant cheetah were found at the Georgian site of Dmanisi, and their study has revealed some interesting facts. The authors estimate that the body mass of that individual would be in the vicinity of 100 kilos, quite larger than the individual from France that I examined and more than twice the average weight of extant cheetahs. The humerus bone is far more stout than in modern cheetahs, probably in relation with the animal’s great mass, but otherwise the proportions of the bones are remarkably elongate.

Here is a photo of the Dmanisi giant cheetah forelimb exhibited at the National Museum of Georgia in Tbilisi (by the way, the small round objects are not cheetah bones, they are actually hyena coprolites!)

OLYMPUS DIGITAL CAMERA

OLYMPUS DIGITAL CAMERA

Other fossil sites, including Saint Vallier in France and Pantalla in Italy, have yielded amazing fossil skulls of A. pardinensis, showing a considerable but not total similarity with modern cheetahs. The skull was proportionally somewhat longer and lower than in A. jubatus, thus resembling more “conventional” cats. But the dentition is very similar to that of the modern cheetah, especially in the fact that the upper carnassial was remarkably blade-like, lacking the inner cusp or protocone. This feature indicates that the animal consumed little if any bone, and, just like modern cheetahs, it would hurriedly eat the more meaty parts if its prey and leave the rest for more powerful competitors.

Here we see a life reconstruction of A. pardinensis (background) shown to scale with a modern cheetah
a-pardinensis-compar-low-res

All in all , we get a complex picture of A. pardinensis. Undoubtedly it would be an extremely fast sprint runner, but its adaptations were a little less refined than in its modern relative, which, combined with a greater body mass, almost surely implied that it would not be a faster animal, in spite of its longer legs. Once A. pardinensis made a kill, its blade-like carnassials allowed it to cut and consume skin and meat very efficiently, but it would probably not stay at the kill site long enough to consume any significant proportion of bone. And it makes sense that, in a world populated by large jaguars, sabertooths like Homotherium, giant hyenas like Pachycrocuta and packs of wolves, the elegant giant cheetah would not risk injury in a fight over a carcass. Just as in the modern cheetah, there was a price to pay for extreme sprinting efficiency. And just like its modern relative, its hunting would have been a true spectacle of nature. Ah, to see such a scene!

Here is a reconstruction of A. pardinensis in hot pursuit of the Pleistocene antelope Gazellospira
acinonyx-pardinensis-and-gazellospira

Iberian lynx: the value of the individual

Early this year we had the privilege of encountering this majestic Iberian lynx in the wilderness of southern Spain. A recent study reveals that the genetic diversity of this species is alarmingly low, something that makes each wonderful individual like this one even more valuable (you can check the study here: http://genomebiology.biomedcentral.com/articles/10.1186/s13059-016-1090-1). It is almost a miracle that we still have the Iberian lynx with us, and it is such a shame that so many of them are killed by cars each year (see a recent news article about the latest lynx killed by a car: http://genomebiology.biomedcentral.com/articles/10.1186/s13059-016-1090-1), not to mention those that fall victim to the ridiculous “predator controls” still practiced in many private hunting concessions in Spain. In spite of genetic problems and centuries of persecution, the Iberian lynx has shown it has what it takes to make a comeback: now it is time for the authorities to get serious about protecting each cat.

One thing you learn from trying to reconstruct fossil creatures is to value the everyday wonder of encountering living, breathing animals in their environment. Unlike the case of our reconstructions, there is so much in them that we didn’t put in there! Portraying the individual is something that is usually beyond the scope of paleontological illustration, because fossils only tell us so much about the variation and subtleties of physiognomy. If only by contrast, that makes it even more enjoyable to be able to portray living, unrepeatable creatures like this male Iberian lynx in his prime.

A few pencil strokes are enough to define the broad proportions of this walking lynx
lince-camina-1

At this stage, I concentrate on the shading in order to create volume and depth, but I already block in some of the spot patterns of the face. The animal’s shadow on the ground contributes to create the feeling of perspective
lince-camina-2

In the next stage of the drawing I gradually add more spots
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I continue adding spots, but as I advance with this process some of the shadows I defined at the beginning are now looking almost too subtle by contrast with the more marked spots,so now I have to deepen them in order to keep the balance between light and dark
lince-camina-4