Evolution


 

 

The exact origin of cats has been obscured by millions of years without fossils.  Carnivores arose about 60 million years ago from a small group of predators called the Miacids.  They were slender, small-bodied forest dwellers with skeletons similar to modern Genets.  They had supple spines, long tails, and retractable claws.  They were well suited to the dense forests that were on the earth at that time.  They were able to hunt in tree-tops and most likely forged on the ground as well.  Their dentition was similar to the modern Palm Civet.

The Miacids followed an evolutionary route that ultimately lead to all modern families of carnivores.  Thirty to forty million years ago, a species appeared that was clearly a Felidae.  It was called "Proailurus".  The oldest fossils came from modern day Eurasia.  It was about the size of a male caracal.  It had more teeth then the modern cat (it had not lost its rear molars of its Miacid ancestors).  It also lived and hunted more in trees.  Its ankles and wrists were capable of wide rotation to grasp branches.  It also had an elongated back which allowed it to move vertically as well as horizontally.  It was also able to use its heels as well as its toes.  This increased the area of foot in contact with branches.  The cat that comes to closest to this today is the Fossa.  These hunt on the ground, but  are equally  adept at climbing and leaping from branch to branch in pursuit of prey.

Following the appearance of Proailurus, there is little in fossil record for 10 million years for Felidae.  Proailurus lived on for at least 14 million years but towards the end of its reign, there is a "cat gap" (23-17 million years ago).  Filling in this gap were other species that were in other carnivore families.  Dogs, bears, hyenas, as well as 2 extinct carnivore families.  These were Nimravidae (Paleo-Cats) and Amphicyonidae (bear-dogs).  The turning point came with the appearance of  "Pseudaelurus".

Pseudaelurus probably descended from Proailurus, but had lost some of its ancient features.  Pseudaelurus' rear molars were greatly reduced and it walked on its toes.  It was like a small leopard in appearance.  The emergence of this brought in a new era in the evolution of cats.  From about this time (17 million years ago), the numbers of Felidae species appearing in the fossil record increased.  At the same time, the number of cat-like species from other carnivore families decreased.  The gradual cooling and drying of the world which gave way to more open savannah woodlands and plains and less dense jungle, caused the increase of Felidae emergence.  From this, prey moved from the jungles to these areas and evolved larger body size and greater speed  to evade predators.  Because of this, Pseudaelurus evolved and grew in size too.  Pseudaelurus laid the evolution foundations that would lead to all true modern cats and many extinct ones.

Saber-toothed cats belong with all modern species in the family Felidae but they represent an ancient lineage which diverged from the evolutionary route that would lead to today's cats.  Both lineages arose from a shared Pseudaelurus ancestor about 15 million years ago.  The saber-tooth lineage spawned some remarkable species which are grouped together in their own felid sub-family.  Two major saber-toothed cats were the Megantereon and Smiloden.

Megantereon and other Saber-toothed cats dominated regular toothed species in Africa for 15 million years.  There were 8 species of these large African saber-toothed cats.  They ranged in size from a powerfully built leopard to as large as a male lion.  Megantereon had the largest of all canines.  It's believed they killed its prey with a canine shear bite.  This left a massive wound to the throat or abdomen.  This technique might have been efficient against juvenile elephants, rhino, and their extinct relatives.  The Megantereon and at least two other African species of saber-tooths lived alongside modern cheetahs, leopard, and lions before dying out around 1.5 million years ago.

 Smilodon was about the same size and weight as the African lion.  Although true,  the body proportions were different then those of any large living felid.  It possessed  shorter, stouter lower limbs, a longer neck, a shorter lower-back,  and a bobtail.  The curved,  saber-like upper canines were long (6 inches or more),  literally flattened, and serrated on the front and back edges.  The skeletal structure suggests that in capturing prey, they did not chase after it for long periods of time.  Their robust  front limbs indicates they hunted prey that far exceeded their weight.  It has been suggested that  with the shortened lower limbs and lower back and the lack of a long tail,  this species used the ambush and stalking technique to capture prey and immobilize it  before giving it  the very lethal bite.  Because they have found remains of these animals  having  neck,  back,  and chest injuries,  they may have preferred a diet of large,  thick skinned animals such as juvenile elephants.  It has also been speculated that they lived in groups like our modern day lion because many bones have been found that have healed even though there were extensive fractures which would have put an animal out of commission for months.  

  

These were at their peak of dominion over a million years ago and then vanished quickly. The final extinction of saber-toothed cats occurred about 10,000 years ago worldwide.  This seemed to have resulted from the extinction of their presumed prey (large ungulates). 

  The other lineage retained the conical tooth shape of the Pseudaelurus ancestors leading eventually to all modern cats (sub-family Felidae).  Compared to their saber-toothed cousins, fossil evidence of these conical tooth shaped cats (especially in Africa), is sparse.  The lion, cheetah, and leopard are the most mysterious.  There's no obvious ancestors in the fossil record until all 3 appear at the same time in Tanzanian deposits that date back 3.5 million years.

 

RESOURCES I HAVE USED AND ALL RIGHTS RESERVED AND ACKNOWLEDGED. ALL TEXT COPYRIGHT MATERIAL. NONPROFIT EDUCATIONAL SITE ONLY:

Lumpkin, Susan and Seidensticker, John. 1991. Great Cats Majestic Creatures of the Wild. Rodale Press, Pa. Pgs 26 and 27.

Hunter, Luke. 2005. Cats of Africa. The John Hopkins University Press, MD. Pgs 34, 40, 42, & 45.

 


 

  

 

HOME