Possible Issues

Minotaurasaurus, whether because of legal issues or contested phylogeny, does not have a lot of presence on the internet. However, there are a few articles online written by Darren Naish and Brian Switek that cover a lot of the information that will be covered here throughout the week and present a number of facts that we have not introduced yet about Minotaurasaurus. Images labeled Minotaurasaurus can be found in many places as well, though this site has compiled a good amount of those images. Prehistoric Wildlife lists the information that we know about the dinosaur, but as that information is limited the page dedicated to Minotaurasaurus is also limited. The Dinochecker website is a bit more wordy, but presents basically the same information as Prehistoric Wildlife with some more detail.

Back to Dinosaurs

It has been quiet around here lately; I have been busy working on other things that require more attention and have made it so I have not been putting much attention in here. However, I enjoy doing this and it is a welcome break from other projects. Plus, we are going to talk about dinosaurs again. More specifically, we re going to talk about large ugly armored dinosaurs again. Anything with a name meaning "man-bull reptile" can be assumed to be an ugly animal. Of course the name, Minotaurasaurus ramachandrani, is based off of the looks of the skull and Greek mythology. The way that this complete skull came to science is complicated, but the specific epithet honors the man (Vilayanur S. Ramachandran) responsible for making the fossil available to science. Because of the complicated history of this fossil, the origin is unknown, but the fossil is likely from the Gobi Desert. The legal status of the fossil is still contested, though not as visibly as it was a decade ago. These are all things that will need to be discussed this week because they are both important and still relevant on a regular basis; probably too often to be honest.

©Nobu Tamura CC BY 3.0

Evolving Swine

As mentioned yesterday, there are not many links for any fossil pigs online. Instead, please enjoy a short video with facts about wild boar, which we know would have a slight resemblance to the history of the pig in question (Strozzi's Pig). Think of this history by proxy as a way to learn a bit about pigs that you may not already know.

Pets Everywhere

We have discussed the origins of a large number of what are now very popular pets. We have looked at the origins of dogs, cats, rabbits, reptiles, fish, horses, turtles, and a lot of other animals. One group we have not looked at that has, at least recently, been more regularly miniaturized and taken from the farm to the living room in many areas: the domestic pig. Belonging to the family Suidae, the domesticated pig has a complicated and long lineage. The domesticated pig is in the genus Sus, a group of animals ranging back to the Miocene, though pigs of the family Suidae are certainly a considerable deal older, dating back to the Oligocene.

Picking pigs to discuss is actually a little more difficult than one mine imagine; there are variable sources of information on fossil pigs and there is actually a lot less information, in total, on fossil pigs than one might imagine as well. Many fossil pigs are known entirely from their teeth and a number are known from their skulls and teeth together. Regardless of how much is known of each fossil pig, there is not a great deal written about any fossil pigs online. There are a number of articles on Enteldonts, but these large artiodactyls are not actually a group of pigs. One pig that has a small internet presence, and we can use as a model for talking about pigs at large, is Strozzi's Pig (Sus strozzi). This pig was very porcine, pig-like, and, as is the case in many wild suids, Strozzi's Pig looked very much like a wild boar or a warthog. Strozzi's Pig was a Mediterranean animal, distantly related to the suids of Africa and closely related to its counterparts from Europe and Asia, which contributed to the displacement and eventual extinction of Strozzi's Pig.

Not So Tiny

We saw earlier this week that Ray Harryhausen made a very nice stopmotion Eohippus for the film The Valley of Gwangi. The reason that the horse was so small is that it was a common misconception that the horse was the size of a Fox Terrier. Many sources have mentioned this size issue many times, but the ultimate source appears to be, according to Stephen Jay Gould, a description of Eohippus written by Henry Fairfield Osborn. It was Gould's opinion that Osborn was excited about the idea of a horse similar in size to a dog and that he was vague in his metaphors to fox hunting when describing the small horse Eohippus. Osborn's comparisons and metaphors make Eohippus out to be a 15 in tall 19 lb horse (the size of a Fox Terrier, obviously); however, Eohippus is approximately 24 inches tall and weighed approximately 50 lbs. There is a difference in the way these animals are measured as well; dogs and horses are both measured from the ground to their withers, the caudal aspect of the shoulders; however, horses typically have a little more soft tissue (muscle and/or fat depending on the breed of dog or horse) than dogs in this area. This is only a problem in comparing the two similarly sized animals in that Eohippus is lacking in the soft tissue area; either way it is still taller than a Fox Terrier. Unfortunately, this sizeable lie is the largest claim to fame, for most people, for Eohippus. It was, of course, also the first recognizable horse, making it an important fossil animal in the history of not only horses, but human beings and, arguably, a large portion of the globe and all of its life. For those more interested in the impact that the descendants of Eohippus have had on the world I recommend starting with this article from Khan Academy.

The Ever Popular Shrunken Horse

If anyone has ever seen a documentary on the evolution of horses they have most likely seen or heard Bruce MacFadden. They may not have known it, but Dr. MacFadden has, for over 30 years now, been one of the premier horse evolution researchers in the world. Therefore, if one were to search for scientific articles on or mentioning Eohippus they could not, and certainly should not, be amazed when the first two results are MacFadden papers from the 1980s on the size of Eohippus and dental evolution using Eohippus as a vehicle for the discussion (and arguments for evolution based on horses too). There are more recent articles as well, of course, including Froelich's systematics paper on Eocene horses and even a description of museum mounted specimens by G. G. Simpson from 1932 (we all know by now I love reading older scientific articles so of course there was going to be at least one!).

Prancing Forest Pony

Coursera is a website that has many free courses from different sources, including a number of universities. One course, on horse care, has a video detailing some of the finer points of horse evolution. This video discusses Eohippus and other early horses, so it is a good starting point for any day with a number of videos on early horses. Aside from this, Eohippus is not much of a screen start. The small horses did have one "starring" role in the 1969 movie Valley of Gwangi. Built by Ray Harryhausen, the small model horses were far smaller than they would have been in real life, but they are still adorably stop-motion animated in great detail.

Dawn of the Horses

©Charles R. Knight

Possibly the most synonymized taxon in the entirety of paleontology, Hyracotherium angustidens was named by E. D. Cope in 1875. In 1876 O. C. Marsh described a similar taxon, naming it Eohippus validus. When Clive Forster noted similarities between the genera in 1932 he reassigned E. validus to the senior genus Hyracotherium. When Hyracotherium was redescribed as a paraphyletic taxon in recent years it was noted that H. angustidens and H. validus were identical species, and Marsh's specific name was considered junior to Cope's, but was considered the only valid genus of the two. Therefore, after all of these taxonomic twists, the animal considered the earliest and smallest of the equid lineage was officially renamed Eohippus angustidens. The official list of synonyms for Eohippus stands at 13 junior names, 3 of which are actually subspecies of other synonyms. Regardless, the small horses are interesting in many ways and, more importantly, are animals that have not been discussed here in full, and are therefore deserving of some time in the spotlight.

People Love Cats

Pseudaelurus may be the most important cat in the entire family line that almost no one has ever heard of. Aside from ending the North American "cat-gap," Pseudaelurus is an important genus because these cats represent the last common ancestors of a diverse array of cats and "near cats." Saber-tooth cats, as a general term, technically fall out of the family line to cats before true felids. As an evolutionary grade, a group of taxa united by shared morphology, Pseudaelurus contains both felids and the true saber-tooth cats (Machairodontinae). This is why Pseudalurus is referred to as the last common ancestor to both saber-tooths and felids; the term "saber-tooth cat" can be extremely confusing because of the true and false labels in addition to the phylogenetic maze of carnivorans in which they settle out. For more information, I encourage everyone to read these articles on false saber tooths at ThoughtCo and Prehistoric Wildlife.

The genus Pseudaelurus has been separated and lumped a number of times over the years. However, the most recent phylogenetic studies (Werdelin et al. 2010 and Piras et al. 2013) have split Pseudalurus over three lineages definitively (unless someone comes along in the future to lump them again). The new genera include Hyperailurictis, Styriofelis, and Miopanther. These each represent a distinct lineage leading to the extinct lineage of American Hyperailurictis felids and the Styriofelis/Miopanther group (including both the extinct lineage of European Styriofelis felids and the extant Felinae which includes domesticated and wild cats). The third lineage retained the name Pseudaelurus and led to the extinct Machairodontinae, the true saber-tooth cats.

Papers That Are Fond of Cats

Pseudaelurus is important in all lineages of felidae because it is the last common ancestor of many different types of cats, but it is also important to people that know, love, and study cats because of this as well. Additionally, Pseudaelurus is the genus of cat that bridged the so-called "cat-gap" in North American fossil history. Tom Rothwell is a paleontologist that knows a lot about Pseudaelurus and the cat-gap. Rothwell has written papers on the phylogeny of Pseudaelurus cats in North America and he has described new species within the genus as well. There are other paleontologists writing papers about Pseudaelurus of course. Papers on Pseudaelurus can be found from as far back as at least 1954 and at least one article on dentition and the skull was written in the 1930s. However, new remains of Pseudaelurus species are described on a somewhat regular basis; clearly this was a genus that was very successful and must have been quite varied to have so many different species identified.

Cat Videos

The internet, it has been said, was built for cat videos. We all know that there is some truth to that statement. The internet is less built for cats as old as species of Pseudaelurus. There are videos on how cats became house pets that can stand in for some of the fact videos we are looking for, but they are just a stand in of course. There is also a German video that presents the facts that we would normally look for in a video. It is a good fact video, if you understand German.

Second of the Proto-Cats

The first of the felids was known as Proailurus. The next most recent descendant is a group of cats known as Pseudaelurus. The genus Pseudaelurus is the last common ancestor of extant felines (mostly small to medium cats, including domestic breeds), pantherines (medium to large cats including lions, tigers, and leopards), and machairodonts (extinct saber-tooth cats). Pseudaelurus consists of twelve accepted species. Originating in Eurasia, species of Pseudaelurus migrated across land bridges into North America, ending what is casually known as the "Cat-gap" from 25 to 18.5 million years ago when few, if any, cat fossils were found.

Figure 3.1 from Evolutionary Dynamics ©IOP Publishing LTD

Lagomorph Illustrations

The average image of Nuralagus is a rabbit looking creature with a very large body in a standing position. Some of these are on rocks and some of them are on grass, but they are all standing fairly still. Considering all of these illustrations, two are probably more useful than any of the others. Roman Uchytel and Darren Naish (I assume there may be others that have repeated this idea) both came up with illustrations of Nuralagus compared with other rabbits, or at least one rabbit, which shows not only how similar its inferred features are to rabbits, but also the size difference between Nuralagus and modern rabbits. The link to Roman Uchytel's site does not show the image I initially wanted to share; however, there is a very interesting version of Nuralagus showing the known skeletal remains superimposed onto the body, like in the Quintana, et al. 2011 manuscript. I appreciate that image though, because the comparison between the holotype of Nuralagus and the European rabbit (Oryctolagus cuniculus), is quite interesting on its own (see below if you missed the image in Quintana, et al. 2011).

Figure from Quintana, et al. 2011

Hopping Papers

Quintana, et al. 2011 introduced the world to the largest rabbit of all time, found on one of the smaller islands of Spain. The idea sounds funnier than it is, but after one looks into Foster's Rule, the so-called "Island Rule", it makes sense in a very interesting way and it can mean a few things:

1) Minorca was separated from continental Europe some time after rabbits had evolved into the recognizable fuzzy tailed garden thieves we know, love (or hate), and sometimes eat.

2) Minorca was a rabbit paradise. Barring any future discoveries of Nuralagus on continental Europe, we can assume that the animal evolved entirely on the island of Minorca and that it must have been a wonderful place for its ancestors to grow and prosper.

3) The unification of Majorca and Minorca caused the downfall of the rabbit Nuralagus by allowing a "cave goat" (Myotragus balearicus) to directly compete with Minorcan rabbits. This should, given adequate testing and sampling from the fossil record before, during, and after the transition provide a solid example of competition hypotheses and Foster's Rule as it relates to size due to competition for limited resources; Someone that is not me that wants to get on that, you are welcome for the idea.

It is interesting that competition with Myotragus may have ended the giant rabbit's rule. Quintana, et al. compare Myotragus and Nuralagus braincases, aerobic capacities, and locomotory characteristics to explain what happens to insular endemic species as they evolve in comparison to their continental cousins. Despite one of these taxa possibly out-competing the other and very different lineages, they had similar evolutionary patterns and morphological traits, relatively speaking.

Bunny Movies

I will not lie and say Easter did not play a part in my choice of animals yesterday. Today I am sad to say there are no funny Easter related videos. We are talking about a giant rabbit, basically, so I was kind of hoping that there would be some tongue-in-cheek Easter mentions here. However, instead we have a few fact sharing videos and no documentary or movie references; it turns out giant rabbits are not ratings generating animals. So, therefore, enjoy the facts and the images of this giant rabbit!

The Non-Precambrian Rabbit

In one of the more interesting stories of scientific history it is said that J. B. S. Haldane, a British geneticist and evolutionary biologist, once wrote (or said) that the only thing that could shake his confidence in the theory of evolution would be the discovery of rabbit fossils in Precambrian rocks. He also wrote a poem about rectal cancer shortly before his death, so he was likely trying to be funny with his rabbit crack as well as a little flippant toward people questioning his life's work and confidence in it. Haldane was an interesting figure regardless of negatives one might find reading about him (he was a vocal supporter of Communism and Joseph Stalin, for example). Anyhow, the question of "how old are rabbits exactly?" has really piqued my interest this week.

The oldest ancestor of rabbits is a 53 million year old fossil consisting of two recognizably lagomorphine (rabbits, hares, and pikas are lagomorphs) feet. These feet belonged to an animal the size of a hamster. However, I do not want to focus on two small feet this week. Instead, let us look at the opposite end of the size spectrum. We have all seen enormous rabbits, but have any of you seen the largest fossil rabbit? I got trapped in a Wikipedia loop of bunnies looking up the Minorcan King of the Hares, Nuralagus rex. Discovered and described in 2011, Nuralagus was approximately 0.5 m  (1.64 ft) tall and may have weighed around 12 kg (26 lbs). For comparison, the largest breed of domesticated rabbits, the Flemish Giant, has an average weight of 6.80 kg (15 lbs).

Nuralagus fossils have been recovered exclusively from the scrubland areas of Minorca, a small island of Spain approximately 402 km (250 miles) south of Barcelona. The discovery of the rabbit fossils in the scrublands indicates that the diet of these rabbits was most likely centered on roots and tubers of the small scrub plants. Some might wonder how an animal like a rabbit, surviving on roots and tubers might become so large. Foster's Rule, also called the "Island Rule" states that large animals with scarce resources tend to evolve to smaller sizes and small animals continue to be small except in the absence of predators which allows lineages to evolve to larger sizes.

Figure 3 from Quintana et al., 2011.