STL Science Center

STL Science Center

30 September 2013

Movies Abandon Us

Hesperocyon does not have any starring roles in movies or documentaries. That is fairly sad considering the fact that Hesperocyon is the first of the canid lineage and a linking transitional form between the the linked canid-felid forms of Miacids and the canid lineage post splitting of the two lineages. Miacids, remember, were arboreal carnivores that hunted in the trees that they lived in. Potentially Miacids could hunt terrestrially as well, but the general life history of the family in the trees is what is known. Hesperocyon is a terrestrial hunter; having lost the arboreal nature of their ancestors and being a great deal better suited to life on the ground. We could certainly have animations of Hesperocyon hunting on the ground as a novel adaptation of the canine lineage. Felines, in opposition, retained the ancestral habit of living and hunting from trees, at least partially, making the hunting of Hesperocyon even more interesting. I am sad we cannot watch an animation of this in the works. Instead, here is an illustration of Hesperocyon hunting (no copyright issues today, just check out the link)!

29 September 2013

Hesperocyon Facts

The Hesperocyon fact pages online are sparse, but there are some. Thankfully, Bob Strauss is highly regular in covering vastly different types of fossil creatures. Therefore, as usual, About has a fairly good fact page dedicated to Hesperocyon. The Department of Mineral Resource of North Dakota has also put together a rather short but nice series of pdfs on the fossil creatures that have been recovered from the soils and rocks of North Dakota. One, of course, is the rather adorable looking Hesperocyon shown here. The page includes maps of the counties in which the fossil has been discovered as well. Additionally, there is a link to a map of other fossil vertebrates discovered in North Dakota on the pdf fact page that is very interesting and well illustrated.

28 September 2013

Hesperocyon the Early Dog

©Robert Bruce Horsfall
Hesperocyon is an interesting step beyond Miacidae, evolutionarily speaking. Miacidae represented the last taxa before the split between felines and canines and Hesperocyon represents the first taxa on the path to full fledged canines. The problem with instant recognition as a member of the canine family is that Hesperocyons are a noticeably transitional species between the mixture of feline and canine features of miacids and the canine features we expect to see in a canid. The heads of Hesperocyons appeared to be very canine like as the snout tapered and elongated anteriorly as we expect in canines. The extended downward arching necks of the animals were a little odd for canids, though we do have extant breeds of canine that have extended downward arching necks.

Cleophas C. O'Harra
Looking at the entire skeleton, it does not appear that either neck or the tail are exceptionally long compared to the early 20th Century fleshed out illustration. The skull is clearly becoming quite a bit more canine in its form and elongation. The premaxilla area of the skull is still a little abbreviated in comparison to modern canines and the canine (eye/upper jaw canine) teeth appear less embedded in the maxilla than do extant canine canines; in fact they appear to be inserted in a laterally sutured "pocket" of bone on the exterior of the maxilla. The skulls of Hesperocyons were shorter, as noted previously, and this may have additionally pushed out the canine teeth to a more lateral position; conversely it could be noted that the extending of the skull over time (disregarding breeds of dog that have been bred to possess exceedingly shortened snouts) allowed for the absorption of the lateral protrusion into the maxilla and streamlining (thinning) of the anterior aspect of the skull.

27 September 2013

My Pick

The previous few weeks of September I devoted to a request kindly worded, but this final week of September I have made my own pick for our discussions. Given that the Miacidae were a very cat and/or dog like group of organisms, I have decided on an early canid mammal. The mammal for this week is Hesperocyon Scott 1890. Hesperocyon includes two species; H. coloradensis and H. gregarius (type). The first of the dog related groups (Hesperocyoninae, Borophaginae, Caninae) to evolve that includes extant canids, Hesperocyon still possessed many feline traits found in the Miacidae prior to the branching of the two groups. The oldest fossils were dated at 42 mya (from Saskatchewan) and the youngest at 31 mya (from Wyoming). These were small canids, only reaching about 4 lbs (1.8 kg) and 2.8 feet (80 cm).

26 September 2013

Ending on A Sadder Note

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.

25 September 2013

U and V Winding Down

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.

P. D. Gingerich. 1983. Wyoming Geological Association Guidebook 34

24 September 2013

Tap Dancing Today

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.

23 September 2013

Skeletons Everywhere!

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.

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.

22 September 2013

Slightly Less Known

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.

21 September 2013

3 Each Day

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.

20 September 2013

Late Evening Post

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.

19 September 2013

Full Circle

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.

18 September 2013

Weird Things

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

17 September 2013

Writing About an Enigma

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.

16 September 2013

No Bodies in Motion

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.

15 September 2013

Motherly Care

©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.

14 September 2013

That Jaw Connection

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.

13 September 2013

Small Curved Animals

©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!

12 September 2013

Ice Aged Fun

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:

11 September 2013

Choosing Wisely

There is so much interesting anatomy, I admit it as someone that does not enjoy studying mammals typically, to choose to discuss today that I am not sure if I want to look at the hindlimb or the nasal trunk of Leptictidium; we are probably lucky that I narrowed it down to those two anatomical features honestly. The hindlimbs of Leptictidium were specialized locomotive machines much like those present in extant kangaroos and rabbits. The kangaroo rat actually provides some very likely mechanics for the movement of Leptictidium through the underbrush.

The fact that it could hop at speed probably made evasion of predators its most likely defense mechanism and, depending on the musculature associated with individual specimens and species, the speed of the Leptictidium and range or types of predators able to chase down the little mammals was probably different in different ecosystems and time periods. To my knowledge mechanical studies have not been done comparing the speeds and gaits of different species of Leptictidium. It is probably important to note that the relaxed gait is not strictly representative of the speed of any individual within a species.

The nasal trunk of Leptictidium that is thought to exist in these small mammals would have more than likely contained some highly sophisticated olfactory senses as it was more a proboscis than it was an actively foraging trunk used for manipulating objects. The dedication of senses in the trunk would allow this small mammal to actively forage day or night and, with other heightened senses nocturnal life would have been an advantageous mode of life for Leptictidium. Considering, however, that the orbits do not seem to be exceptionally large or geared toward containing eyes that were adjusted to a nocturnal lifestyle, it appears to be more likely that Leptictidium was a crepuscular (dawn and dusk) predator of insects. Then as now insects would have been very active at dawn and dusk and Leptictidium could have used its heightened senses of smell and hearing to detect insects foraging at a distance and hidden by dense vegetation from the sight of Leptictidium.

10 September 2013

Follow the Bouncing Mammal

It is something like follow the bouncing ball, but furrier and probably a little more dangerous than a ball, because Leptictidium has some good size teeth. The postcranial skeleton of Leptictidium has been studied and described many times over, as well as compared across time and formations. In 2006 the Eocene Leptictidium and Early Oligocene Leptictis, of Europe and Wyoming respectively, were compared. Unfortunately that paper is not so easy or free to get a hold of as Meehan and Martin's paper detailing the discovery of those Wyoming Leptictid mammals, those this time from the Paleogene. Reading about even similar small mammals is interesting, but it would be very nice to be able to read the original Storch and Lister paper naming and describing Leptictidium nasutum if you have that ability. It is not apparently available widely online and it is only in German it appears.

09 September 2013

Leptictidium Hopping Into Your Heart

Leptictidium is a bouncy little mammal. As such, the videos we have for Leptictidium are very "hoppy". In the words of LeVar Burtan, "you don't have to take my word for it", just watch this:

08 September 2013

Firendly Little Guys

There is not a doubt that Leptictidium falls into what the internet is these days calling the "dawwww" and "squee" categories of adorable little animals and the genus is as such expected to be a hit with the kids of the world. Not as many sites exist for fossil animals outside of the Dinosauria, however. About's Bob Strauss has written another succinct and well delivered page on Leptictidium that would be suitable for younger readers, and that is a good thing. Australia's version of of ABC has a question and answer page up about Leptictidium that would most likely be of interest to younger readers as well.

07 September 2013

Small Fossils

Leptictidium nasutum
Leptictidium is actually a fairly exceptional little mammal. The general rule in fossils is that the smaller you are the more likely it is that parts of your body, or the entirety of your remains, will be lost over millions of years. However, Leptictidium fossils are fairly abundant and not only of good quantity, but also of good quality; many of the fossils found are entire or nearly entire skeletons. This is due in part to the fact that these fossils are slightly younger than the fossils we typically discuss and because these small mammals lived in the underbrush of forests. The underbrush of forests contain a lot of materials that can quickly bury animals and, in forests near swampy lands, the additional material inundating the forest floor during flood events also added to the positive preservational bias. Additionally, forest fires, a common occurrence in a natural system, would have caused the suffocation and burial of these small mammals fairly easily. Regardless of the method of preservation or reason for exceptional preservation, numerous well detailed individuals have been discovered and unearthed throughout Europe and a great deal of the anatomy of Leptictidium is known and can be studied in the future as well.

BBC model
The fleshing out of past creatures is often difficult without skin impressions but, again thanks to the wonderful preservation of specimens of this animal, the fleshy details of Leptictidium are a little more well known. In some instances the overall body shape of the soft anatomy of Leptictidium has been preserved as a carbonized film that looks like a dirty halo around the skeletal fossil. The finest details of the face have been little preserved, but extrapolations have been fleshed out using what details have been preserved and with modern analogues filling in any gaps of hypothetical behavior and form. The analogue most often used for Leptictidium are the elephant shrews (Family Macroscelididae) of Africa. Also insectivorous, the features that make elephant shrews successful have been incorporated into Leptictidium, to a point, to make up for missing details of the soft anatomy and the comparison between the two sets of animals has drawn parallels and enhanced understanding of the skeletal structures as well. The proboscis seen in documentaries and in many fleshed out illustration is based in large part on the elephant shrew proboscis, which is actually kind of funny to see in action.

06 September 2013

Surprise Mammals!

We have discussed mammals here before, and usually I announce when we will deviate from our dinosaur topics, but I received a very kindly worded request not too long ago to discuss mammals again and I wanted to surprise everyone, request maker included, rather than build up anticipation, etc. However, it is a great pleasure to deviate from the norm for the month of September and discuss, though not my favorite group in the wide world of animals, the mammals of the early days of the age of mammals. Technically I have mentioned this week's little mammal before on here. A while back when discussing the age of giant birds I discussed very briefly a prey item for some giant birds; a small mammal with shrew-like qualities and the locomotion of a tiny kangaroo: Leptictidium. Leptictidium is a genus comprised of five species: L. auderiense, L. ginsburgi, L. nasutum, L. sigei, and L. tobieni. These small mammals were forest dwelling bipedal insectivores that were successfully spread across the forests of Europe during the Eocene but went extinct as the forests gave way to open grasslands in the Oligocene. Today they have left us with no descendants and little soft anatomy, but a fair assortment of well preserved skeletal anatomy.

05 September 2013

No One Knows Me

Nyasasaurus is a little known dinosaur. Even the name of the lake that lends its name to the dinosaur has changed in the years since it was discovered and initially named. Nyasasaurus is included in some encyclopedic works on dinosaurs but does not have its own specialized books (neither those geared toward scientists or general audiences). Nyasasaurus did gain some popularity in the media when the latest study named it as one of the oldest dinosaurs to have existed. Images of Nyasasaurus that were shared due to this news were typically snippets of the Mark Witton illustration shown here earlier in the week; however, images from the study were also shared with the public. Probably the best image was the one shown below which highlights some of the better aspects of the discovered bones and has cross sections of the humerus shown as well, for all of the histology fans out there.
The humerus specimens of Nyasasaurus parringtoni seen in (a) anterior and (b) posterior views, as well as (c) complete cross-section in transmitted light, (d) cross-section through the entire cortex, and (e) cross-section through the outer portion of the cortex. (f) Rearticulated sacrum in right lateral view with interpretive drawing. (g) Posterior presacral vertebra in right lateral view. (h) Partial posterior presacral vertebra in dorsal view. (i) Anterior cervical vertebra in left lateral view with interpretive drawing. (j) Anterior cervical vertebra in left lateral view with interpretive drawing. Scale bars: (a,b,f-j) 1 cm, (c) 4 mm, (d) 1 mm, (e) 500 nm.

04 September 2013

The Minimal Facts

It is always a difficult call to make when a scientist or group of scientists name a new species on very little material. Nyasasaurus is based on such little material that it is almost amazing that we can even consider it definitively a dinosaur. Looking back at papers that we have read this week it is apparent that there were enough characters to definitively announce Nyasasaurus as a reptile and, based on the consensus interpretation of the characters it does appear to be one of the most basal dinosaurs. The vertebrae are scattered around the body (a handful of cervical, a couple thoracic, and a few post-sacral) and the only other bone available for comparison and analysis is a humerus from the right forelimb. This bubble drawing was created to represent the potential area of the body and its dimensions:

03 September 2013

Southern Dinosaurs

Support for the hypothesis that dinosaurs originated in the southern areas of Pangaea are explored in a paper that was begun by Alan Charig's colleagues with his help and then finished posthumously in December of last year. The paper is the same research referenced in the radio interview posted yesterday. The paper identifies Nyasasaurus as either the earliest dinosaur or the sister taxon of the Dinosauria. The age of the fossils are explored as well, extending the origin of the Dinosauria backwards in time, making the group older than previously thought. The paper can be retrieved from an outside site not associated with the Royal Society, but be aware that there are copyright rules to be observed and respected and do not be amazed if the link stops working sometime given those things.

02 September 2013

Radio Programs

Nyasasaurus does not have any dedicated videos; however, there was a radio program last year, Quirks and Quarks, that is hosted by CBC. The interview is fairly informative, and it is a nice listen. I think today I will let the radio do the talking and make this a very short post!

01 September 2013

Coloring A Rare Dinosaur

Nyasasaurus remains are rare and websites designed to educate children specifically about Nyasasaurus are pretty much non-existent. The best to offer in terms of that is the page about Nyasasaurus. That page is another perspective showing Nyasasaurus as a carnivorous dinosaur. This is a coloring page that sort of makes up for the lack of information available to younger readers, but given the lack of information all around concerning Nyasasaurus it is not too amazing that there is not as much to share with any specific age groups about this dinosaur.