Specializing in the care of cats and kittens

Paris Hill Cat Hospital

2825 Old Route 12
Paris, NY 13456

Monday - Thursday 8am - 6pm
Friday and Saturday 8am - 5pm
Sunday 10am - 5pm

Natural History of Cats

Veterinarian Tom Rothwell
Natural History - American Museum of Natural History

While a Research Associate in the Division of Paleontology, I focused my research on fossil members of the family Felidae (fossil felids, fossil cats). I continue to study primarily the fossil felids of North America, focusing on the specimens present in the Frick-AMNH collection of fossil mammals.

Contact me at:
Tom Rothwell
Paris Hill Cat Hospital
2825 Old Route 12 • Paris, NY 13456

Email: info@parishillcathospital.com

Curriculum Vitae

Ph.D., Vertebrate Paleontology
Department of Earth and Environmental Sciences
Lamont-Doherty Earth ObservatoryColumbia University, New York City

Doctor of Veterinary Medicine, 1976
New York State College of Veterinary Medicine
Cornell University
Ithaca, New York

Click here to go to Cornell's NYS College of Veterinary Medicine

Bachelor of Science, Chemical Engineering
Syracuse University, 1971


Pseudaelurus validus
Pseudaelurus validus
  • 2004. Rothwell, T. New felid material from the Ulaan Tologoi locality, Loh Formation (early Miocene) of Mongolia. In G.C. Gould and S.K. Bell (editors), Tributes to Malcolm C. McKenna: his students, his legacy. Bulletin of the American Museum of Natural History 285: 157-165.
  • Rothwell, T. 2002. Phylogenetic systematics of North American Pseudaelurus (Carnivora: Felidae). Bulletin of the American Museum of Natural History (In Press)
  • Rothwell, T. 2002. New felid material from the Ulaan Tologoi locality, Loh Formation (early Miocene) of Mongolia. Bulletin of the American Museum of Natural History, Number 285 (Chapter 12).
  • Rothwell, T. 2001. A partial skeleton of Pseudaelurus (Carnivora: Felidae) from the Nambé Member of the Tesuque Formation, Española Basin, New Mexico. American Museum Novitates 3342:1-31.
  • Rothwell, T. 1982. Aerobic and anaerobic conditioning of the three-day event horse. USCTA News June: 6-8.
  • Rothwell, T. 1981. The AHSA drugs and medications rule-know your facts, avoid needless elimination. USCTA News April: 20-21.
  • Rothwell, T. 1980. Re-training the horse with navicular disease. Long Island Horse World 2:30-31.
  • Rothwell, T. 1978a, The tragedy of hip dysplasia. In: Caras, R. (ed.) Dog Owner's Bible, pp.277-280.South Hackensack: Stoeger Publishing Company.
  • Rothwell, T. 1978b, The crucial business of immunization. In: Caras, R. (ed.) Dog Owner's Bible, pp.32-38.South Hackensack: Stoeger Publishing Company


Research Statement

Nimravides thinobates, Nimravides pedionomus
Nimravides thinobates
Nimravides pedionomus

I am a student of natural history. I am interested in the anatomy of felids (cats) and how knowledge of this anatomy can lead to understanding evolutionary relationships within the family Felidae, the sub-order Aeluroidea and the order Carnivora. My first body of work at the American Museum, my doctoral dissertation, concentrated on the anatomy of the earliest fossil felids of North America. These cats entered the North American continent approximately 17 million years ago, and left a fossil record that spanned approximately 5 million years. I compared the anatomy of these extinct taxa to modern cats, and then hypothesized on their relationships. As a result of this work, the earliest felids that entered North America now have genus and species names as well as morphological characters that are attached to these names. This is indeed a good start. However, much more needs to be done. For example, it has been published that the felids alive today are closely related and that they share a common ancestor that lived only three or four million years ago. I am interested in investigating whether that is true, and if so, in determining just who that ancestral felid might be.

My present research involves the earliest saber-toothed cats of North America. The first fossil evidence of these special felids, with their elongated upper canines, begins to show up in North American localities approximately 11 million years ago. At the American Museum, we have a magnificent collection of these early saber-tooth cats. I am studying the anatomy of these fossils in great detail and I will be comparing their anatomy with that of the earlier fossil felids and to the cats who are alive today. I will then use computer programs to analyze this data. The computer will provide hypotheses, or suggestions as to the relationships of all of these cats. A scientific goal is to determine who the ancestor of the earliest saber-tooth cats might be.
There is another feline question that I would like to help answer. If all of the cats alive today are closely related (and they appear to be very closely related), then it may be possible to identify their common ancestor in the fossil record. If the common ancestor of today's cats can be identified, perhaps then we can find out why it survived and why other potential ancestors went extinct. If we are to prevent further extinction within the family Felidae; if we wish to save the great cats that are still with us, the lions, the tigers, the snow leopards, surely then we must find out how and why the cats that survived to the present did so.




cladogram: This is a manually constructed cladogram that I use when teaching. It demonstrates the three major clades, or divisions of living families within the order Carnivora. In blue is the large and diverse group known as the arctoids. The canids (dogs, wolves, coyotes, etc,) are represented by a single lineage in green. The cats, hyenas, mongoose and viverrids are the red group known as the aeluroids. Characters 1, 2, and 3 are hypothesized to unite all of Carnivora:

Character 1 is use of the upper fourth premolar (P4) and lower first molar (m1) by all members of the order Carnivora to eat meat. This is called the P4/m1 carnassial apparatus.

Character 2 is near and dear to all veterinarians who practice on dogs and cats. Character 2 is the presence of anal sacs. Anal sacs are hypothesized to be present in the ancestor of Carnivora due to its widespread distribution among all of the living members. Anal sacs are lost or reduced only in bears and in the aquatic families (seals, sea lions, walrus and otters).

Character 3 is the primitive carnivoran dentition: 4 premolars and 3 molars in both the upper and lower dentition.

Character 4 unites all of the living families of Carnivora. Character 4 is the development of an ossified bulla covering the middle ear, a bony covering for the ear apparatus. The primitive carnivorans (carnivoran = member of the order Carnivora) had a single-chambered bulla covered by cartilage.

Ventral skull

Character 6 diagnoses the four closely related families referred to as the aeluroids or the sub-order Aeluroidea. Character 6 is a modification of the primitive single-chambered bulla: the development of a two-chambered bulla. Evidence of character 6 can be seen in the ventral skull and in the basicranial photograph.



Data Table Results: There are arguments for and against sexual dimorphism being the explanation for some character differences between species of fossil felids. Arguments for include: (1) Sexual dimorphism is seen in modern felid species, at the very least in body size and skull length in small felids. (2) The fossil felids Pseudaelurus skinneri and Pseudaelurus stouti display differences in c--p3 length that could also be interpreted as sexual dimorphism. (3) The fossil felids Pseudaelurus intrepidus and Pseudaelurus marshi are size and temporally equivalent. Specimens of the two species are sometimes found in the same paleontological localities (quarries). Arguments against include: (1) A similar range in c--p3 length and dentary height and width is not seen in the fossil felid Pseudaelurus validus. Pseudaelurus validus and some modern species do not exhibit sexual dimorphism in the lower jaw. (2) 

Modern assemblages of felids sometimes contain at least two species that are indistinguishable in jaw length. (3) The p error for the hypothetical Pseudaelurus intrepidus--Pseudaelurus marshi (male-female) species that I created in this tab le (0.0001) is far outside the range of p error seen in the four modern species studied (0.28--0.008). The results appear inconclusive, due primarily to the variability of the sexual dimorphism displayed by different species of living felids. However, if Pseudaelurus intrepidus and Pseudaelurus marshi were indeed sexually dimorphic members of the same species, the males and females differed far more than any of the four living felids that I studied.

Stratigraphic chart

Stratigraphic Chart: This is a rough estimate of stratigraphic ranges for various fossil felids. As new specimens are discovered, or as fossil localities are dated more precisely, these ranges will change. The first North American felids arrived during a major dispersal from Eurasia to North America that began approximately 20 m.y. ago. The early fossil felid record of Asia is poor. Only a small number of specimens have been recovered from early and middle Miocene localities. Therefore, the stratigraphic range of Pseudaelurus in Asia is less certain than Europe and North America.
My present felid research project is a study of the early North American saber-tooth cats, often referred to as the machairodont felids. Nimravides and Machairodus are two of the earliest North American saber-tooth cats. NA Felis refers to the stratigraphic range of fossils of the modern felids.


Nambe felid skeleton
FAM 62128, the Nambé felid skeleton:
From 1932 to 1965, Childs Frick sent numerous collecting parties into the fossiliferous terrestrial localities of Tertiary North America. The Frick Laboratory assembled a magnificent collection of fossil mammals as a result of these expeditions. Now referred to as the Frick Collection, this assemblage of fossil mammals is housed in the collections of the Division of Paleontology of the American Museum of Natural History. Within the Frick Collection is the world's most comprehensive fossil felid collection. Fossils of the first felids to arrive in North America, in the late Hemingfordian, were collected in localities of the Sheep Creek Formation of Nebraska and the Tesuque Formation of New Mexico. The earliest known partial felid skeleton (FAM 62128) was recovered from the Nambé Member of the Tesuque Formation of New Mexico and described by me in 2001. Photo by Chester Tarka of the AMNH.

Nambe skull
By carefully identifying and measuring the anatomical structures present in this early felid skeleton, I was able to determine how closely it resembled other fossil cats and the cats who are alive today. Photo by Mick Ellison .upper third incisor (I3), upper canine (C), upper first premolar (P1), alveolus or socket for upper second premolar (P2 alv), petrosal (P), mastoid (M), paroccipital process (PP).


Left front paw
This is the left front paw of FAM 62128. Third phalanges (ph3) are the bones of the toes that include the cats' claws. The ph2 lateral concavity is referring to the place where this cat could retract his claws, just as today's cats do. Mc5, Mc2 are the fifth and second metacarpal bones. Photo by Mick Ellison


articulated right rear paw
This is the articulated right rear paw of the New Mexico skeleton (FAM 62128) in dorsal (A) and ventral (B) views.(ses) = sesamoid bones, nav = navicular, cu = cuboid, ent = entocuneiform, lat conc = lateral concavity of second phalanx. Photo by Mick Ellison

Diastema Jaw\
diastema jaw: This is an illustration of the type specimen of Pseudaelurus marshi, a fossil lower jaw of a cat who lived in North America in the middle Miocene, approximately 13 million years ago. The illustration is featured in the original description of this fossil, written by the paleontologist Malcolm Rutherford Thorpe in 1922. I scanned this illustration and then added the reference to the distance from c-p3. Early on in my research on the early cats of North America, I realized that the space between the lower canine (c) and the third premolar (p3) was a character that could possibly differentiate species in both extinct and modern felid taxa.

The coronoid process (CP) or vertical ramus of the lower jaw of felids is another anatomical feature that is variable in fossil felids. A is Proailurus lemanensis, the earliest known felid, with a short, wide, and erect coronoid process. This cat lived approximately 23 million years ago. B and C are felids that are approximately 16 million years old. Their coronoid processes have become relatively taller, but are still erect. The felid labeled D has a tall coronoid process that is no longer erect. It slopes to the right, to the rear of the cat's skull. This cat lived in North America approximately 13 million years ago. E is a modern, extant, or living cat (Panthera leo, the lion). This coronoid process is tall, sloping, and has a terminal hook.



Felid skull
FAM 61835, the Echo Quarry felid skull: This is the basicranium, the left side of the base of the skull of a North American cat who lived approximately 16 million years ago. By comparing this part of the skull with other extinct carnivores and with cats that are alive today, I am able to hypothesize or speculate on the relationships of this cat. Photo by Tom Rothwellectotympanic (T), limit of the caudal entotympanic chamber (ce), paroccipital process (pp), anteromedial process of the auditory bulla (am), petrosal (P), paroccipital process (pp), entotympanic (E), hypoglossal foramen (hf).

Pseudaelurus stouti
This wonderful fossil (UNSM 25490) is a partial skull, the type specimen of Pseudaelurus stouti, a small cat who lived in North America approximately 14 million years ago. It is housed in the University of Nebraska State Museum. We are looking at the upper dentition. This cat was similar in size as our domestic cats of today. However, notice that this cat has four upper premolars. The cat in your house or barn would have P2, but no longer has P1. The modern, domestic cat has evolved without a first upper premolar (P1). It has lost this anatomical feature or character. Photo by Tom Rothwell

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