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Ice Aged Fun

September 12, 2013, 9:34 am
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Leptictidium is a fun little mammal. The people behind the Ice Age series of movies adapted Leptictidium to the series made one of the funniest characters in the world of mammals: Scrat (I have alternatively found that the character was based off of another small mammal, but for today, he was based off of Leptictidium). I really do not feel that I can top the popular culture representation of Leptictidium beyond showing a clip of Scrat doing the kind of ridiculous things he was animated to do:

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Small Curved Animals

September 13, 2013, 6:00 am
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©Nobu Tamura
During the Late Triassic and Early Jurassic therapsids called Cynodonts roamed the Earth and bridged gaps between what is a mammal and what is a reptile. One small animal (now classified as a reptile) that is of interest in this gap is Oligokyphus. Consisting of four species (Oligokyphus triserialis(Hennig E, 1922), Oligokyphus major(Kühne WG, 1956), Oligokyphus lufengensis(Luo Z & Sun A, 1993), and Oligokyphus sp.) this small detour from the mammalian topic of the month of September is well warranted. Originally named in 1922 by Hennig as a mammal, Oligokyphus has been redescribed many time as new species have been discovered and the remains of a vestigial joint in the jaw that retains the articulation of quadrate and squamosal has caused this small furry creature to be reclassified as a reptile. What can such a close association between reptile and mammal tell us about the small animals that lived with the dinosaurs and survived the extinction events at the end of the Mesozoic? How is a fossil representing a reptile genus included in the Cynodontia, a suborder that includes all living mammals? These are questions that we can hopefully answer this week, and that may cause the typical programming to be just a bit different from what we are used to here!
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That Jaw Connection

September 14, 2013, 10:28 am
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The jaw of Oligokyphus is odd. For all of the Mammalian characteristics that are present in the body and impression fossils (or carbon films) of Oligokyphus, the jaw is still reptilian enough to have called for a reclassifying of this animal as a reptile. The quadrate, a bone in the area where the lower jaw (in reptiles a complex set of bones and in mammals the singular mandible or dentary) meets with the skull, abuts the squamosal, a bone of the post orbital skull. In most Therapsids quadrate and articular are seen as ear bones already; mammals have 3 ear bones consisting of what once were the quadrate, articular/prearticular, and angular bones in reptilian jaws. The fact that Oligokyphus still possesses a distinct quadrate makes it a very basal (at best) mammal and rather likely that it is actually still more reptilian than mammalian in its composition. Therapsids, Cynodonts, and Tritylodonts (the family of Oligokyphus which is named so due to its tricuspid teeth) are a tricky set of animals. These animals are jigsaw puzzles of transitional skeletal elements linking reptilian and mammalian heritages. Oligokyphus is one of the major players in that jigsaw puzzle of anatomy.

The overall anatomy of Oligokyphus is, as has been noted, rather mammalian with the notable exception of the skull morphology. The high sagittal crest on the skull is apparent in the skull image, but it is not truly appreciated until seen in respect to the entire body. The sagittal crest allows for increased muscle mass and attachment in the skull and typically adds to the closing of the jaw, meaning that the bite force of Oligokyphus was probably fairly significant for a 20 inch (50cm) long animal. All of that bite force, however, was dedicated to the grinding of plant matter; Tritylodonts, and Oligokyphus in particular, were strictly herbivorous. The rest of the weasel-like body would have been dedicated to digesting the vegetable matter that was ingested.
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Motherly Care

September 15, 2013, 8:33 am
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©Michael Long
Despite the questionable affiliation of Oligokyphus the general consensus on Cynodontia, mammalian and reptilian, is that the parents provided care for the young. Due to the generally accepted diagnosis of Oligokyphus as a reptile the common view that reptiles do not care for their young adds even more jumble to exactly what this animal was like. Very much mammal like but reptilian enough to be a reptile, would Oligokyphus have laid eggs and then cared for the hatchlings? Maybe it was the opposite, that Oligokyphus gave live birth and abandoned the pups. It is more likely that the first was situation was true with the parents bringing back food for the hatched (or maybe live born) young instead of possessing mammary glands with which to feed its young. As yet no carbon residue images or mummified remains have shown evidence to the contrary, but they would be quite the find if glands were discovered in Oligokyphus. Regardless of the nature of gestation of the young in this animal, some parental care is assumed to be apparent, and as such images like this are probably fairly accurate. Also kind of cute.
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No Bodies in Motion

September 16, 2013, 8:12 am
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The video library of Oligokyphus is pretty much nonexistent, so that means that we have to improvise today (that is if I can spell anything; I had to retype that sentence numerous times). As such, I would like to take the time today to look at the size of this little reptilian furball. Cynodonts in general were smaller animals and are thought to have lived, typically, in small burrows that were either primary or secondary holes (secondary meaning they stole it from someone else). Additionally, as we have discussed, the Tritylodonts are said to be completely herbivorous. Looking at analogous size in modern rodents and reptiles both, animals of this size are typically not completely herbivorous, though there are some that are to be sure; Iguanas, for example, are strictly herbivorous and can easily attain sizes larger than Oligokyphus. The first thought I had, at least, when looking at the size of this animal were rats on the mammal side and small monitors on the reptile side; both groups have carnivorous or omnivorous diets. Size, of course, does not always correlate strictly to diet with notable exceptions; our planet's largest animals tend to be herbivores. My point on size is that the size of this animal tends to make me think its diet, without looking at the teeth, would consist of other small mammals and reptiles as well as insects, rather than salads. However, it is a good thing that teeth tell a good story of the life of an animal and it is fortunate that we have those teeth to tell us that story.
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Writing About an Enigma

September 17, 2013, 10:21 am
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Tritylodonts and Cynodonts are, as we have said many times over, rather interesting riddles. They have been written about many times over, and have also been the subject of studies that go with those articles many times over as well. Hans-Dieter Sues introduced us, in 1985, to the first discovered Oligokyphus in North America. Additionally, we have records from China as well. Both papers describe Lower Jurassic animals, which should not really be new information, but it is important to back up other's findings and to agree on date data. Unfortunately, Hennig's 1922 initial description of the genus is not available to us online, or I would suggest that definitely be read. Lack of that piece, however, can be made up through inter-library loans! Potentially.
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Weird Things

September 18, 2013, 10:06 am
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I was looking up something on Oligokyphus just now and apparently enough people have searched "Oligokyphus dinosaur" that it pops up on Google. We are here to teach, so of course my first response to that is that there needs to be a little more outreach concerning the nature of these enigmatic little devils. First and foremost, Oligokyphus is a Synapsid whereas dinosaurs, and extant reptiles including birds (that is a different discussion altogether as many of us know), are Sauropsids. The important difference here is the skull morphology. Synapsids have what is called a synapsid skull in which the skull is perforated below the squamosal bone by a single temporal fenestra. Sauropsid skulls can be one of three forms: Diapsid, Anapsid, and Euryapsid. Diapsid and Anapsid skulls can still be found today, in birds/lizards and turtles respectively, while the Euryapsid condition was an alternative skull found in extinct Ichthyosaurs and Plesiosaurs. Oligokyphus, as a rather odd mammal-like reptile, has a Synapsid skull while retaining a jaw joint between parts of the lower jaw known as surangular and articular and a quadrate bone in the skull (refer to earlier discussions in the week on mammal vs. reptile jaw articulations). That skull morphology alone excludes Oligokyphus from the dinosaurs, so please pass that along to anyone you hear refer to Oligokyphus as a dinosaur!

From Introduction to Paleobiology and the Fossil Record, Benton and Harper

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Full Circle

September 19, 2013, 11:19 am
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Oligokyphus has been quite an interesting little friend this week. Not quite mammal. Not all reptile. Certainly not a bird. Oligokyphus is a very interesting little transitional form; a so-called "missing link". Bridging the gap between mammal-like reptiles and what we could consider the most basal, or first "true" mammals. The fuzzy nature of Oligokyphus is such that, ignoring the enigma of classification, makes for an interesting little puzzle about a cute little animal. It is a widely known Cynodont despite not being highly popular. Cynodonts tend to be, as their name implies, "dog toothed" possessing both canines and molars and tended to lay eggs; remember that we left the oviparous/viviparous reproduction of Oligokyphus open to debate. Oligokyphus was potentially oviparous, but is also close enough to mammals that there is still that chance that they were viviparous. Regardless, the cute and fuzzy little almost-mammals are quite interesting and worth much more popularity than they have so far accrued.
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Late Evening Post

September 20, 2013, 6:57 pm
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I apologize for the lateness of this post ladies and gentlemen; I had some oral exams this afternoon and did not feel like writing this morning. I want to tackle a family this week, not a single genus as I normally do. The family that we will discuss is a somewhat large group of medium sized cat like carnivores. Dating from the Paleocene and Eocene epochs, Miacids stuck around as an important family for about 29 million years.The Miacidae family is a paraphyletic group, meaning that it does not include all descendants of the species. Miacidae was a transitional family that ushered in the rise of the modern Carnivora. It should be an interesting family to discuss as a family, despite being a much larger group than we typically discuss here.
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3 Each Day

September 21, 2013, 7:49 am
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Attribution: GFDL
There are 19 genera in the family Miacidae. This works out really well in that we can discuss three genera each day without really detracting from any given genus too much; sometimes things work out nicely. The largest genus for today is the genus Miacis, which clearly lends its name to the family. Consisting of 16 species, Miacis was generally characterized by a long slender body, longer forelimbs than hindlimbs, and a dog-like pelvis. Equipped with needle-like claws, the Miacids in general, were well suited to an arboreal life in the trees. The genus Miacis is probably the most well studied of the family and has revealed a lot about diet, consisting of small mammals, birds, reptiles, and possibly eggs, as well as the intelligence of the family. Studies measuring the size of the brain show that proportionately to body size Miacis was a pretty smart genus of dog hipped cat-like basal carnivora.

The other genera of the day are Eosictis and Messelogale. Both genera consist of a single species and are considered to be quite typical members of the family, sharing many of the anatomical characters of the Miacis members. Eosictis was named in 1945 and Messelogale in 1982.
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Slightly Less Known

September 22, 2013, 3:20 am
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Oodectes skull (L. lateral, ventral, and dorsal) and dentition.
Three more genera today; Palaearctonyx, Miocyon, and Oodectes. Palaearctonyx consists of one species, Palaearctonyx meadi Matthew 1909 while the other genera are made up of 4 species (Miocyon) and 2 species (Oodectes). Unlike most of the other members of Miacidae that we have looked at so far Palaearctonyx is thought to have been an omnivorous little mammal instead of a strict carnivore. Miocyon and Oodectes are obligate carnivores, as far as we can tell. Palaearctonyx also has the most complex taxonomic history; it has been reassigned once or twice, nothing too difficult to follow. The heads of these animals, as we can see, are still low crested and equipped with canine teeth that are well suited to biting into prey items.
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Skeletons Everywhere!

September 23, 2013, 8:12 am
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Paroodectes feisti
Genera of the day: Paramiacis, Paroodectes, Procynodictis. Paramiacis consists of two species, P. exilis Filhol 1876 and P. teilhardi Mathis 1987. These species were united as one species under P. exilis as sexual dimorphism examples. Mathis 1987 separated the two as individual species rather than retaining the hypothesis that they were male and female exemplars. Paroodectes  consists of a single species, P. feisti. Springhorn (1980) described this species as being very nearly related to the genus Oodectes which was discovered in North America despite this being a European species. He determined that the animal was arboreal and that it was a good example of how closely together, overall, the European and North American members of the family are united by their character traits. Procynodictis is made up of two species P. progressus and P. vulpiceps and is considered to be a direct ancestor of one of the first canid animals, Hesperocyon. Named initially by Wortman and Matthew in 1899, Procynodictis could make for a rather interesting study in transitions all by itself if given the time. The species P. vulpiceps is considered by some sources to be potentially synonymous with Miacis gracilis.

References:
Mathis C. 1987. "Précisions sur le genre Paramiacis Mathis (Carnivora, Miacidae)" in Bulletin du Muséum national d'histoire naturelle (Paris).


Springhorn, R. 1980. "Paroodectes feisti new genus new species the 1st miacid carnivora mammalia from the middle eocene of messel west germany". Palaeontologische Zeitschrift (54(1–2)): 171–198.
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Tap Dancing Today

September 24, 2013, 11:48 am
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Tapocyon robusts (T. occidentalis)
I have to say, it is discouraging that articles are a bit more rare than I would like for the greater majority of the family Miacidae. Miacis is a member of the family that has been studied a bit more than others, and as such, has more articles dedicated to it like this one on a partial skeleton from Wyoming. Two of the genera of today, Prodaphaenus and Quercygale, are sparse on articles and species; P. scotti, Q. angustidens, Q. hastinsgae,and Q. helvetica making up the entirety of the two genera. Prodaphaenus is almost nothing more than a note in the history books also, having very little information overall disseminated about it. Quercygale, however, is a bit more of a cosmopolitan and well known animal. Conjectured to be a basal carnivore predating the split between canines and felines, as all Miacids are, Quercygale is thought to be close to that branching (thus making it the most advanced of all the Miacidae) and an immigrant from the Asian continent into Europe. The three species have all come from different countries with Q. angustidens Filhol 1872 coming from Quercy France, Q. hastinsgae Davies 1884 coming from Headon Bedes, England, and Q. helvetica Rütimeyer 1862 originating in Switzerland. Tapocyon is the newest-to-us genus in the triplet today. Discovered in 1930s California, specifically Ventura County and the city of Oceanside, California, Tapocyon remains consist of jaw bones in the original discovery and partial skeletons from subsequent discoveries. In 2003 Wesley and Flynn set out to redescribe what were then three species (Tapocyon dawsonae, Tapocyon robustus, and Tapocyon occidentalis). That paper synonymized the type species, T. occidentalis with T. robustus.
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U and V Winding Down

September 25, 2013, 1:19 pm
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Vulpavus ovatus
Uintacyon, Vassacyon, and Vulpavus are just a few more genera in the family Miacidae. Together they are comprised of 15 total species (8 in Uintacyon, 2 in Vassacyon, and 5 in Vulpavus). Uintacyon and Vassacyon are linked in that a species of Uintacyon was reevaluated and determined to be unique enough to warrant reclassification as a new genera called Vassacyon; U. promicrodon is the type species of Vassacyon and is synonymized with V. promicrodon Wortman and Matthew 1899 (according Gingerich 1983). Vassacyon is considered to be the largest members of the family and some of the largest early mammals of the Eocene. Uintacyon, however, had a larger distribution and was in abundance throughout the Eocene and Paleocene as well, though with a much more limited North American range in the latter ages of the genus' existence. Vulpavus is the oldest named of the three genera (Type: Vulpavus palustris Marsh 1871 ). Weighing in at about 1.2 kg and with a distribution that encompassed most of North America from upper Canada to the southern United States, Vulpavus was a successful arboreal predator in that 92, a modest number of records, partial skeletal discoveries are attributed to Vulpavus across North America.

Reference:
P. D. Gingerich. 1983. Wyoming Geological Association Guidebook34

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Ending on A Sadder Note

September 26, 2013, 11:09 am
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Miacidae has been an interesting family to look at. Essentially they would have, had they been domesticated, the all around pet for everyone. If you like dogs, they are like dogs. If you like cats, they are a lot like cats, and they climb trees rather well. The last two genera, Ziphacodon and  Xinyuictis round out the family and, though not a lot of information is readily available about either genus, they do exemplify the cosmopolitan geography of the family. We have seen species from Europe as well as America and Ziphacodon rugatus M. R. Thorpe, 1923 is not an exception. Xinyuictis tenuis Zheng et al., 1975, however, is an exception in the family in that it was discovered in central Asia; the Jiangxi province of China to be exact. The species were identified, initially, approximately 100 years apart as well, making them an even more interesting end of the line (Marsh 1872 originally describes Ziphacodon). If all of the illustrations and descriptions have not painted a satisfactory picture of these little carnivores for you this week, check out African civets; they have essentially an identical body shape and are approximately equal in size.
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Short of A Prize

October 22, 2013, 5:52 am
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Thomas Huxley described and named Acanthopholis in the 19th century. Some of the writings he created in which the dinosaur is mentioned have survived long enough to make it online. However, these writings are far from free and, honestly, are quite a bit more expensive than a one or two page historical document would appear to warrant; though I am not a historiographer nor am I an appraiser so I cannot say with certainty that this is true. Regardless, at around $45 a piece, some of the articles from the Geological Magazine printed by the Cambridge University Press can be obtained. Ken Carpenter tackles armored dinosaur phylogeny in a book he edited called The Armored Dinosaurs and mentions the positioning of Acanthopholis within the family and this reading is far more easily available at any large library or here in piecemeal if one wanted to simply skim over an article.
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Something New to Consider

October 23, 2013, 2:44 pm
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In 1999 Superbiola and Barrett reviewed the materials attributed to Acanthopholis and determined that the material was not distinct enough to merit being anything more than fragmentary bits of the average Nodosaur. As such, they determined the name to be a nomen dubium and to disregard its existence. However, the name is still in use and considered valid, apparently, by the majority of research that I have seen. Nestled in the family Nodosauridae, Acanthopholis is a small member of the family with small oval dermal ossifications with spikes in the shoulder and neck area and along the spine. Nomen dubium or small Nodosaur? You decide.
©Mariana Ruiz
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Dubious Favorite

October 24, 2013, 3:17 pm
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Acanthopholis, meaning "spiny scales", is somewhat famous, despite being dubious in its distinctions, from time to time.  Unfortunately, the debatable nature of things due to fragmentary remains as well as the 1999 study that determined it to be a nomen dubium. Regardless, it has shown up on websites for information purposes and not in many other places. In fact, toys, books, and even modifications to video games seem to be lacking for Acanthopholis. It is just too bad that there is not much in the popular culture world for this dinosaur.
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Adding Up!

October 25, 2013, 10:54 am
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©Karkamesh (accuracy disputed)
Adasaurus mongoliensis, meaning Ada's lizard, is a small theropod dinosaur described and named in 1983 by Rinchen Barsbold. Ada is a Mongolian mythological character considered to be an evil spirit, and this Dromaeosaurid dinosaur certainly could be considered an evil looking animal. Unfortunately the relationships of Adasaurus and other Dromaeosaurids are not well understood because Adasaurus is represented by fragmentary fossils of the skull as well as post-cranial skeleton. These fragments, however, have lead to the idea that Adasaurus should be considered a member of the subfamily that includes Dromaeosaurus and Utahraptor, the Dromaeosaurinae. These are heavily built members of the family. Conversely the animal is shown to be a part of the Velociraptorinae subfamily which consists of smaller and more gracile members of the family.
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Being Average

October 26, 2013, 6:22 am
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Unknown but clearly based on the Timothy Bradley illustration
The thing to know about illustrations of Adasaurus is that they all appear to be very uniform in terms of looking like Dromaeosaurids. They always appear rather gracile regardless of how stocky they seem to appear, and they are always portrayed with the toe claw characteristic of the majority of Dromaeosaurs in an extended position. It is a sad occurrence that there is not imagination typically portrayed in these dinosaurs, but that is how it is.
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