July 1969

There are a number of events turning 50 this year. Paleontology is not left out of 50 year old events. One of the most important, in my opinion, is Bulletin 30 of the Yale Peabody Museum of Natural History. Bulletin 30 included one of the most iconic scientific illustrations of my childhood (see below), drawn by Robert Bakker, and accompanying the description by John Ostrom of an "unusual theropod" found in Montana known now as Deinonychus antirrhopus (discovered in 1964). The inspiration for Jurassic Park's Velociraptor antagonists, Deinonychus was a small to medium sized bipedal dinosaur approximately 3.4 m (11 ft) long that lived 115 - 108 million years ago. Hypotheses of Deinonychus behavior and the 172 page description of its osteology by Ostrom have fueled comparisons to birds and produced images of an intelligent, pack-hunting dinosaur. The 120 mm (4.7 in) toe claw reconstructed from YPM 5205 by Ostrom was enough to inspire nightmares even before that annoying kid spoke up in Jurassic Park. Estimated to weigh in at 100 kg (220 lbs) Deinonychus was beefy and adding strength and a giant claw to an animal that was likely rather fast for its size only adds to the nightmarish qualities of this Cretaceous predator.

Happy 50th naming month to one of my favorite, and one of the most frightening, dinosaurs that we know of, Deinonychus antirrhopus!

Deinonychus antirrhopus ©Robert Bakker

Week of Moving

When Keichousaurus came across my screen the first time I thought it was an impressive appearing nothosaur but that it had a funny little head. Then I realized everything about this aquatic reptile was small, and a little funny. Its rudimentary flippers still appear to be mostly pes and manus, rather than true flippers, and its elongate neck with a short faced head is almost somewhat comical. Most of these fossils are found as entirely complete animals. Their intriguing morphology and the completeness with which they are often found, as well as the fact that specimens are not much longer than 2.7m (and many smaller specimens are known), Keichousaurus fossils are highly sought after as attainable collector's pieces. Though their abundance makes this possible, it does not necessarily make it acceptable. The variation of known fossils is, as with any animal group, appreciable. The morphological variation that has been lost due to the sale, or simply retention by finders, of these fossils to collectors hurts population studies as well as our knowledge of the evolution of aquatic reptiles overall. However, we do know a lot about Keichousaurus, as this WizScience video shares:

Returns and New Beginnings

I am back to having the time to write a little bit here and there every day. There are many good animals to start with as we restart these (mostly) daily entries. I decided that, since this is the restart of this blog we should go back to the roots of the roots of the first project I worked on after the inception of this page. The only way that makes sense is to talk about an animal that is a member of the group that gave rise to the animals that I originally worked on. My first project was describing a set of plesiosaur vertebrae, and the animals that preceded the plesiosaurs were a group that we call the nothosaurs. One genus, Keichousaurus (consisting of K. hui Young 1958 and K. yuananensis Young 1965), was first discovered in China in 1958 by Hu Chengzhi and described by C. C. Young. This genus, like other nothosaurs, possess a long neck and tail, short head (relatively), and paddle-like hind and forelimbs; the forelimbs being more paddle-like were thought to be more important in locomotion than the hindlimbs. This locomotion was also thought to resemble that of plesiosaurs and has been described as "underwater flight", though this is still largely hypothetical at present. The holotype species (K. hui) is represented by numerous fossil animals, including pregnant individuals indicating live birth or ovoviviparity (hatching in the uterus and being "born" live) in Keichousaurus.

We might think these animals would be quite large, given that their plesiosaur descendants are quite large animals. However, many of these nothosaurus are extremely small, ranging from 15-30 cm (6-12 in) in length. There are individuals known to reach 2.7m. Despite the long neck and tail that we see in illustrations of Keichousaurus, that long neck is actually quite short, in respect to what we usually think of for long-necked animals (think of giraffes and long-necked dinosaurs, as examples). Of course, that neck is relatively long for these small animals!

©Nobu Tamura

Fancy Pets

The "Mexican Walking Fish" (Ambystoma mexicanum) is probably one of the first non-mammalian animals that I ever interacted with (aside from actual fish) in an extended capacity. My mother was tasked with feeding the Ambystoma in one of Indiana University Bloomington's biology research labs back in the late 1980's. This is also where I first hung out (I was maybe 8 so "was tolerated" may be a better description) with graduate students and learned how to play Tetris, but those are stories for another time. We generally do not call Ambystoma Mexican Walking Fish, which is good because in the traditional nomenclature sense they are actually salamanders and not fish at all. Most know them as those strangely adorable pink aquatic pets known as Axolotl.

The story of Axolotl is amazing, endearing, and almost somewhat ridiculous; but we are not going to learn much more about Axolotl today as they are a means to an end for us here. I will share that they love uncooked beef liver. Also, I was inspired to talk about them today because a friend that works at the Boston Museum of Science shared a post about an upcoming exhibit featuring these adorable little salamanders. Salamanders in general are fairly recognizable by most, though there is sometimes confusion over names (e.g. newt vs. salamander) and appearance (think Axolotl vs. any other generic "salamander" that comes to mind). We could discuss how newts are salamanders and why Axolotl look different from Tiger Salamanders (which they are closely related to), but we are going to talk, now that we all have a picture of salamanders in our heads, about fossil salamanders from the Permian known as Apateon.

Senckenberg Museum of Frankfurt
Photo  by Ghedoghedo

Often preserved as flat impressions on slabs, these Permian temnospondyls are primitive amphibians that, like the Axolotl, are neotenic; meaning that they retain juvenile traits, such as the external gills seen in Axolotls, in their mature adult forms. This is often referred to as pedomorphosis also. Researchers have shown that these traits are retained in large numbers of these animals and they were so populous that we have a wide swath of ontogenetic or life cycle examples of animals in this genus to show that we are not just looking at odd young from many different groups. We have, of course, living examples to draw from as well. Many interesting things are known from these fossils, but probably one of the most intriguing things, to me, is the number of large group fossils and the detail in both the large group fossil assemblages and single animal fossil slabs that exist for Apateon. The genus Apateon actually consists of 7 species with Apateon pedestris von Meyer 1840 containing the holotype for the genus. As with many exquisitely preserved slab fossils, Apateon was originally discovered in Germany, a country with a rich history of excellent freshwater fossil diversity and preservation, and specimens have been dated from 295.0 to 290.1 million years ago.

Apateon pedestris Natural History Museum, Bonn University
Photo by Ghedoghedo

The skeleton of these Permian amphibians can be seen in this image from the Natural History Museum of Bonn University, which is actually quite a feat. The skeletons of Apateon are very weakly ossified, so the identifiable vertebrae, ribs, and limbs are truly exceptional and speak directly to the preservation of the fossil. Additionally, the orbits are fairly identifiable and, because we can see where the eyes would have been, we can see that the snout and the area of the skull directly caudal, or behind the eyes, are very short. We can say that Apateon had a very small head rostrocaudally (front to back) but also a very wide skull and very large eyes. If we turn our attention to those limbs we can just make out the digits. We know from more splayed out fossils of the limbs that there were four digits on the forelimb (on the "hand") and the hindlimb as well.

Groundhog Day

In 2014 a fossil skull from Madagascar introduced us to a "groundhog-like" mammal of the Late Cretaceous. The animal was named Vintana sertichi in Krause et. al, 2014. This mammal was estimated to weigh approximately 9.1 kg (20 lbs) and was relatively short, as we can see in Nobu Tamura's reconstruction below. Flanges found in the skull are not well understood and appear to have no homologous structure in modern relatives, but their purpose could still be discovered with more discoveries of the fossils or further investigation into the family as a whole. Regardless, the endocast of the brain did reveal very large olfactory bulbs. We know from this that Vintana had a good sense of smell and likely used this trait actively and frequently in its normal day to day life. It may seem that a single skull of a small mammal is not that important, however, mammologists and mammal paleontologists think this skull is pretty amazing. The reason that they feel this way is because this fossil skull represents possibly the best preserved skull of any gondwanatheres; a group of southern hemisphere cynodonts that lived from the Cretaceous to the Miocene. Actually, another interesting facet of Vintana is that, though it was discovered in Madagascar off the east coast of the African continent, it belongs to the mammalian sudamericidae family which translates literally to the South American family of mammals. In fairness, a largenumber of gondwanatheres belong to this family and have been discovered in Africa, making Vintana not the first and probably not the last

©Nobu Tamura

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Animals Not Often Known

This week I decided that we really ought to get a little bit of knowledge into an odd group of animals that we have never looked at before. We have explored a lot of marine animals including fish, mammals, and reptiles. There is a set of aquatic mammals that we have not yet explored. This group of marine mammals is known, largely, today as the "sea cows." One of the genera that best represents the group is a globally known genus called Metaxytherium. The genus Metaxytherium consists of 8 species (M. albifontanum Vélez-Juarbe and Domning, 2014; M. arctodites Aranda-Manteca et al., 1994; M. crataegense Simpson, 1932; M. floridanum Hay, 1922; M. krahuletzi Depéret, 1895; M. medium Demarest, 1822 (type species); M. serresii Gervais, 1847 and M. subapenninum Bruno, 1839) represented from the Miocene into the Pleistocene. Dugongs, the family (Dugongidae) of organisms to which Metaxytherium belongs, is a capable of living in both marine (salt) and freshwater systems and Metaxytherium was not an exception with taxa being discovered in both coastal and inland fossil deposits. Metaxytherium looks, skeletally, very similar to extant manatees and dugongs; you can see the skeleton of M. floridanum below.

Photo by Ryan Somma

Fossils and Parrots

When one searches fossil parrot two things appear. One is a report of a partial tarsometatarsus (a bone in the foot) from Siberia that was dated to 16-18 MYA. This is interesting, but it is a very small part of a parrot. A proto-parrot from Wyoming also appears regularly in the search list. This animal, shown below, does not have the familiar head shape of parrots, but does possess other features of parrots and is a whole bird; though it is in the typical bird state of a fossil which is to say that it is nearly pressed entirely flat. This fossil comes from the Fossil Butte Member of Green River Formation and has exceptional preservation, despite the crushed nature of the fossil. If you were to look closely at the neck you can see tracheal rings, the cartilage circles that keep the trachea ("windpipe") open so animals can breathe. Other fossil parrots are known to science, but many of them are associated with much older discoveries, so the papers describing these finds are not high on the search returns. These include parrots found in the Miocene of Nebraska (Wetmore 1926), New Zealand and Australia (latest paper: Worthy et al. 2011), and the Czech Republic (Mlíkovský 1998). There are other papers describing fossil parrots as well, but some describe the same finds mentioned above or are reviews of what we know about the parrot fossil record.

Cyrilavis colburnorum photo by Ian N. Cost

Enjoy some Images

Today, enjoy some imagery of Temnodontosaurus. Also, enjoy some toy reviews. The second video is a model from CollectA and is particularly interesting as it includes a pup in the process of being born; it is admittedly a little odd.

Also enjoy this short clip that is said to portray Temnodontosaurus. Because there are not a lot of Temnodontosaurus videos, definitely spend some time checking out this cartoon about Mary Anning as well.

Short on Facts

I always find it to be a little odd when there are few places to find facts on what should otherwise be a fairly well-known animal. Considering Temnodontosaurus' place in fossil finding history and its giant eyes, it ought to be a little bit more well-known online. However, aside from a few tribute videos and some animation tests, there are almost no videos online. There are also fewer fact pages than we would normally expect for such an important fossil animal. There is a short encyclopedia entry on KidzSearch (a site we have not used lately) and a very slightly longer entry on the Ancient Animals Wiki. A more informative source of information that includes a slightly more in depth article and a list of facts can be found on Prehistoric Wildlife, a site we have found useful to learn from for a long time around here.

Celebrating Lyme Regis

©Dmitry Bogdanov

The holotype of Temnodontosaurus platyodon (originally Ichthyosaurus platyodon) is approximately 6.1 m (20 ft) long and was discovered in 1821. Although the name means "cutting tooth lizard" the fossil is best known for two radically different reasons. The first is that the orbits and the 25 cm diameter sclerotic rings indicate that the eyes were approximately 20 cm (8 in) in diameter, making these the second largest known eyes in any animal. Prior to a 2008 dissection of a rare Colossal Squid (Mesonychoteuthis hamiltoni) which has eyes approximately 27 cm (11 in) in diameter Temnodontosaurus had the largest known eyes. The second most important reason that Temnodontosaurus is well remembered is because this large ichthyosaur was one of the first fossils found by Joseph and Mary Anning in 1811; it was initially described as a crocodile. Joseph outlived Mary by a few years, but Mary was the true force in the family fossil collecting business despite being largely deleted from the literature of the time by the geologists to whom she sold her fossils. Anning also led geologists (including Buckland, Agassiz, Owen, and Conybeare among others) on expeditions, taught them how to collect fossils from Lyme Regis, and trained their field assistants and wives how to collect fossils. Temnodontosaurus may be well known for being discovered by the Annings, having large eyes, and being one of the first known ichthyosaurs, but it is not the best known of Anning's discoveries; that distinction belongs to (depending on who one asks) either her 1823 discovery of Plesiosaurus, or her 1828 discovery of what later became known as Dimorphodon. During this week we will talk a little about Temnodontosaurus and Mary Anning both every day. The reason for that, for those interested, is that many of Anning's discoveries were made or published during December and her life was actually strangely influenced by the month. Additionally, it was recently announced (14 December) that a movie based on part of her life, titled "Ammonite" will begin production in March 2019. Anning and December seem intertwined and Temnodontosaurus was her first big find. It all goes together for a fitting end to the year.

Also, I just realized this is blog post #2500. Hooray!

Videos of Giant Sauropods

Invest a little time in learning a little bit about Sauroposeidon today with WizScience and Dinosaurs Unearthed:

The Tallest Sauropod

Sauropods were enormous animals, for the most part. They certainly have a wide range of sizes, but the absolute largest sauropod ever known was discovered in southeast Oklahoma and described in 2000 by Wedel, Cifelli, and Sanders. Trace fossils, in this case footprints, from Oklahoma, Wyoming, and Texas have long been associated with the animal as well and, despite the holotype consisting of only a few cervical vertebrae, many more bonebeds and isolated fossils have been discovered in these states since 2000. Named the "lizard earthquake god" that was "perfect before the end" Sauroposeidon proteles was estimated to have possessed a neck approximately 11.25–12 m (37–39 ft) long based on the largest cervical vertebra of a sauropod known, which measured in at 1.4 m (4.6 ft) long. That is a fairly large singular bone; almost as tall as my mother actually! It also makes the neck about 2 m (7 ft) longer than the next longest sauropod neck (belonging to Giraffatitan).

CC BY-SA 3.0 Stephen O'Connor

It's in the Name

It was mentioned earlier this week that Protarchaeopteryx, as a name, translates literally to "Before Archaeopteryx". This poses a small problem because Protarchaeopteryx is a Cretaceous archaeopterygian and Archaeopteryx itself is a Jurassic animal. Geologically speaking, Archaeopteryx predates Protarchaeopteryx by approximately 25MY; though it is important to note that the accepted span of existence for Archaeopteryx is 150MYA - 125.45MYA and Protarchaeopteryx shows up in the fossil record at 124.6MYA. This means that they are not, temporally, that distant from one another. This does not necessarily reflect their phylogenetic relationship to one another. Now, the reason that we brought up the names is that the implication of the name is not actually what the name means. What I mean, and what Ji and Ji meant by that in 1997, is that Protarchaeopteryx did not come before Archaeopteryx, but rather it possess characters which appear to place it in a phylogenetically primitive position in relation to Archaeopteryx. The justification for the name as assigned by Ji and Ji was that "...it [Protarchaeopteryx] is regarded as more primitive because it has a more elongated tail, more robust pelvic girdle, longer and larger hind limb, and unfused proximal metatarsals [than Archaeopteryx]." These characters, it may not require stipulating, are more derived in Archaeopteryx. To better understand the description and read the translated version of that 1997 paper, please see the reference presented below.

Reference:
Ji, Qiang, Shu’an Ji, and Translated By Will Downs. "A Chinese archaeopterygian, Protarchaeopteryx gen. nov." Geol Sci Tech 238 (1997): 38-41.

Caveats of the Internet

Any time that one searches for anything discussing birds, dinosaurs, and/or evolution, one must be aware of the confusing and argumentative cyclone of websites that are out there. Looking up an animal like Protarchaeopteryx is a part of that rule and certainly not an exception. A safe place to start is something like the WizScience video below that just presents facts that we know about this dinosaur without adding conjecture or argument to what is presented.

Of course, we cannot assume that all of the videos and websites are as neutral as those put forth by a group like the team behind WizScience. That being said, there are websites that do avoid the arguments on the internet by presenting information (and being fairly regularly updated to maintain that information) without allowing comments; it really can be as scary as I am making this sound when a website discusses the dinosaur-bird transition and key fossils and allows for commenting. Pages that are safe include:
Encyclopedia Britannica
The Natural History Museum of London
Age of Dinosaurs
Dinosaur Jungle
Enchanted Learning

Early Feathers

We always love a fossil that we haven't talked about or a fossil that has had a lengthy absence and we are talking about it for the first time in a really long time. This may or may not be one of those times; I feel like we have covered Protarchaeopteryx robusta before, but searches of the entries on the blog turned up nothing. That is almost 8 years worth of entries to search though, and considering that with this year as an exception of every day entries, that is a search of almost 2500 entries. Regardless, the small "Before Archaeopteryx" feathered theropod is an interesting dinosaur that was discovered in the Yixian Formation of China in rocks that belong to the Aptian age of the Early Cretaceous (approximately 124.6 MYA). There are questions about the validity of the animal; some discussion has involved its relationship to another small dinosaur, Incisivosaurus (we may visit this animal next week to follow up). However, with that relationship in question and not cemented or ignored, another relationship is still alternatively proposed for Protarchaeopteryx; that this animal represents a basal oviraptorosaurid. Despite this ancestral mystery, we do have some idea about what the animal ate (likely mostly herbivorous but sometimes supplementing this diet with meat) and what it was covered in (symmetrical, flightless feathers) and we can therefore form a few hypotheses about the way that Protarchaeopteryx lived in and interacted with its environment and other animals.

Protarchaeopteryx holotype at the Geological Museum of China
CC BY-SA 4.0

Two papers

There are two important papers that everyone interested in Rubeosaurus should take a moment to read today. These papers discuss, first, some interesting remains of "Styracosaurus" ovatus in which the authors, McDonald and Horner, introduce new remains attributed to this species and then analyze the characters and describe the phylogeny of the animal. This paper contains the naming of the new genus, Rubeosaurus, based on this material and is therefore important in knowing where the dinosaur came from and what was known about it previous to its naming in a new genus in 2010. The second paper is about a subadult specimen of the genus that was discovered somewhat recently and described by McDonald in 2017. This description is actually a revisiting of a previous description of another dinosaur (Brachyceratops) and places a young animal within the genus Rubeosaurus. Additionally, this description causes the name Brachyceratops to be considered invalid, or as we more commonly say in paleontology, it is a nomen dubium (a problem name).

It Refers to Brambles

One might imagine that with a name like Rubeosaurus ovatus the person naming the dinosaur may have been poking fun at someone, but the name actually means "Bramble lizard" and references the appearance of the ceratopsian frill that makes up a good portion of the known skeletal elements. Originally named by Charles W. Gilmore in 1930 as a species of Styracosaurus, Rubeosaurus was split from that genus in 2010 by McDonald and Horner following a phylogenetic analysis conducted using new material attributed to what would be renamed Rubeosaurus. The ceratopsian dinosaur has a similar frill to its close relatives Styracosaurus and Einiosaurus. These frills all possess large parietal fenestrations and are bordered by large conical processes surrounding these cranial bones and highly ornamenting the skull. A singular and immense nasal horn is also present in Rubeosaurus, just as in its close relatives.

©Lukas Panzarin CC BY 2.5
From McDonald and Horner 2011

Papers of Many Measures

There are many Dimetrodon papers. A significant number of those papers are descriptions of different finds of Dimetrodon from various different places. The original naming papers would be most interesting, if we had them somewhere online. We do not, to my knowledge. However, we do have the first Dimetrodon species known from Europe, the first from outside of North America actually, which was found in the Bromacker assemblage. This is a Lower Permian formation in and around the Thuringian Forest of Central Germany.

There are other descriptions of Dimetrodon as well. Some of these regard the jaw muscles of the interestingly shaped skull of Dimetrodon. Other venture into describing how Dimetrodon may have regulated its temperature using its unique sail structure. The structure of the sail is, of course, a constant subject of study. Like any other body part, the sail could be subjected to injury as well, and studies have certainly been conducted that on said injuries.

Many of these studies together have led to phylogenetic studies of Dimetrodon. The pelycosaurs, in general, are in an interesting position in the evolutionary tree of synapsids. One of the papers I enjoyed reading when I first learned systematics and began dealing with trees is this paper by Ken Angielczyk which uses Dimetrodon as an example species in how to think about trees (otherwise discussed as "tree thinking") how to use them to understand relationships between taxa.

Not A Dinosaur

Pelycosaurs are not dinosaurs. As Dimetrodon is a pelycosaur, Dimetrodon is also not a dinosaur. This has mostly been eroded from the popular psyche, though there are still vestiges of Dimetrodon's inclusion in the world of dinosaurs out in the modern world. These videos will make sure that everyone knows what a Dimetrodon is and is not.

Emily Graslie (she is a professional science communicator, so expect a well delivered video) on Brain Scoop:

A top ten list of facts. This video again addresses the fact that Dimetrodon was not a dinosaur straight off the bat. It then lists some interesting facts about Dimetrodon. The video includes a lot of images and video game animations.

New Old Animals

Sphenacodontids ("Wedge point tooth") are a group of synapsids that are known from fossils found across Europe and North America from ages between from the Late Pennsylvanian to the Middle Permian. The most well-known examples of not only sphenacodontids but also pelycosaurs is the large headed apex predator known from Texas and Oklahoma (mostly), Dimetrodon ("Two measures of teeth"). The genus Dimetrodon actually consists of 13 recognized valid species; though we regularly hear Dimetrodon referenced as though it is a single species (generally the type species, D. limbatus Cope 1877). The general description of Dimetrodon species is a group of animals presenting with tall laterally compressed skulls, a large dorsal sail, and a tail composed of upwards of 50 caudal vertebrae, accounting for a significant portion of the total length of the animals. The sail is what most people think of when they think of Dimetrodon, but these pelycosaurs are actually named after their teeth, which consist of 1 - 2 pairs of large caniniform teeth and large incisors in the front of the mouth and smaller teeth caudally. Also intriguing in the skulls of Dimetrodon species are primitive nasal turbinates, appearing to indicate a capability of warming and cooling air as it was inhaled and exhaled and what appears to be a transitional morphology of the ear that would give rise to the mammalian ear. The story of the mammalian ear is far more complicated than the previous sentence makes it sound, but this intermediate ear morphology is important in overall ear evolution.

There are many reasons that Dimetrodon is an interesting animal to study and, given time this week, we can get into some of the studies that have been done with disparate species of the Dimetrodon genus. Dimetrodon will always stand out because of their importance in the evolutionary history of synapsids, their unique morphology, and, personally, because the first model I ever built was of a Dimetrodon standing on a rock. It is very possible that this was the model kit (I was young and it was forever ago, but this brings up the memory of building it).

 Also, here is a nice illustration of a few of the species of Dimetrodon scaled to one another by Dmitry Bogdanov.

©Dmitry Bogdanov