STL Science Center

STL Science Center

31 January 2017

Brains and Skulls

The brains of animals are, to many, some of the most intriguing organs that one can study. I do not work with brains but they influence a great number of aspects of what I do study and, as such, are worth noting in the wider scope of my work. They develop unique shapes and intriguing areas of the brain have been poked, prodded, and described for a very long time in science. Many researchers are very interested in how the brains of fossil animals are shaped and what they were capable of. To that end, many fossil animals have had endocasts of there skulls molded and modeled. One study that discusses aspects of the braincase, not necessarily endocasts, was published by Oliver Rauhut in 2004. In this paper, the structure of neurovascular canals, pneumatic areas of the braincase, and the morphology of individual elements of the neurocranium are described. Apomorphies and implications for related theropods based on this cranial morphology are discussed as well, which is important in placing Piatnitzkysaurus in its family tree and filling out neighboring branches. Rauhut described another fragmentary skull in 2007 as well, this time focusing more on dental elements and teeth. One of the first mentions of the dinosaur, though, is also available for reading today (to a limited audience, sorry).  Published in Science in 1979, Bonaparte's article Dinosaurs: A Jurassic Assemblage from Patagonia described a number of Argentinian dinosaurs, including Piatnitzkysaurus.

30 January 2017

Shorts and Amateur Film

Piatnitzkysaurus does not appear in any actual movies or documentaries. The animal has managed to capture the interest of many online content builders though, which means that it semi-frequently has been featured in shorts and films made with toys and cutouts. Some of the best short movies that have been published have featured only illustrations (one such here:, minus one spectacular video. The video below is worth not writing any more about the videos.

29 January 2017

Facts About A Dinosaur

All of the usual websites plus some more rare sites and even sites we have never used have useful information about Piatnitzkysaurus. As with any massive amount of information, there are duplicate sets of information published online about this particular dinosaur. A WizScience video exists that covers many of these facts as well as adding some interesting notes and covering the entire narrative with detailed illustrations and interpretations of the dinosaur. As such it is almost more useful than reading multiple sites, but should probably not be used as substitute as much as it should be viewed as an addition to the reading. That reading should certainly include the sites mentioned here in April of two years ago; we did cover this dinosaur, but its lack of support/popularity online at the time was embarrassingly lacking for how well we know the dinosaur. These sites can be found at this link. Additional sites include CoolDinoFacts (minimal information) and Age of Dinosaurs.

28 January 2017

Piatnitzky's Lizard

Named and described by Jose Bonaparte in 1979 for the Russian born Argentinian paleontologist Alejandro Matveievich Piatnitzky, Piatnitzkysaurus floresi is a 4.3 m (14 ft) 450 kg (990 lb) bipedal Jurassic carnivore of Patagonia. The dinosaur is known from two partial skeletons, one of which is composed of a partial cranium and postcranial elements. Significant portions of postcrania constitute the second individual initially described by Bonaparte. The dinosaur is similar to many other contemporaneous predators, though separated by oceans. and general environment.
Photo by Francisco Paez

27 January 2017

Seeing the Little Giant

Neuquensaurus was, without any doubts, a small sauropod dinosaur but still dwarfed the average human being. The height of the animal may not relay that fact and a flat two dimensional image does not really prepare us for the human to dinosaur weight comparison of this animal, but when we consider that the dinosaur was approximately 8 m long we can assume that its abdomen was much larger than a human being and its weight (which I have found no estimates for) was considerable.

This is still a visibly small sauropod when compared to other titanosaurs; it makes one wonder why this was considered to be a member of Titanosaurus but it may have been considered a juvenile at one point or another. That is not the point today, of course, the topic for Friday is fantastic art that shows the dinosaur of the week in a dramatic or dynamic pose where we can really appreciate the history of the fossil and the work that has gone into not only describing the animal but also its environment. The best image available for Neuquensaurus is dynamic image that does not show the environment as much, but does give us a glimpse of contemporary predator relationships and the sleekness of this small sauropod. Possibly more agile than its larger cousins, Neuquensaurus was likely capable of rearing back, much like Apatosaurus and Diplodocus are often shown doing in documentaries, movies, and illustration; however, this dinosaur is doing nothing of the sort. Instead, it is defending its young from an Abelisaurus simply using its size and ability to stay between the predator and the immature animal. The brachiosaurid cranium is a slightly bewildering detail given the dinosaur's close relationship with Saltasaurus which possesses a much more ovate cranium (in typical illustrations), but we can overlook this aspect and leave it under the idea of artist interpretation. The osteoderms on the back of the animal are clearly modeled after those shown regularly on Saltasaurus and, assuming the close relationship between the two animals was reflected in this skin armor, its resemblance to the other animal's morphology is nicely placed and looks quite natural.
©Martin Chavez

25 January 2017

Speculative Characteristics

There are a number of characteristics of Neuquensaurus that set the sauropod apart from other members of its family. These include dorsoventrally flattened posterior caudal centra as well as a well developed tibial tuberosity. These skeletal characters are not the most exciting characters that could possibly set Neuquensaurus apart from other sauropod dinosaurs. However, the more intriguing, and speculative characteristic that has been hypothesized to have existed on Neuquensaurus skin. The osteoderms that are hypothesized to have developed on the skin of Neuquensaurus would have acted like an armor plating on the dinosaur, much like its cousin Saltasaurus is though to have possessed. This hypothesis is based on the discovery of a pair of osteoderms uncovered in Patagonia in 2005 that were associated with a Neuquensaurus skeleton. These osteoderms were illustrated in the Salgado paper shared yesterday. If anyone missed the illustration, here it is for your perusal:
From Salgado, et al. 2009; osteoderms are labeled B

24 January 2017

History Lessons

The Neuquensaurus australis phylogeny is complex and has an interesting history (feel free to disagree if phylogenetic history is not exciting to you!). Originally described as a member of the genus Titanosaurus by Lydekker in 1893 (Titanosaurus australis), Neuquensaurus was bounced around the titanosaur family tree. Lydekker's 1893 description of the dinosaur does not appear anywhere online or I would, as I often do, recommend reading this to learn more about the holotype remains. However, this is not the end of the Neuquensaurus tail an there are many other papers that reappraise the materials and their placement. One such paper (also not available online unfortunately) is the result of Friedrich von Heune's inspections of the Neuquensaurus material. In 1929 von Heune placed a number of contested elements of Neuquensaurus into a new genus (Laplatasaurus). Von Heune noted that many of the elements of Neuquensaurus were not entirely dissimilar from Titanosaurus and so the name held until 1986 when Jaime Eduardo Powell named the new genus Neuquensaurus based on the material being less similar to Titanosaurus than even Laplatasaurus was. Powell's assertions based on his dissertation's redescriptions (titled Revisión del titanosáuridos de América del Sur)were not accepted until 1992, when the book Los Dinosaurios y Su Entorno Biotico: Actas del Segundo Curso de Paleontologia in Cuenca was published. Powell was not renaming Titanosaurus australis at this time though, as it had been reassigned to Saltasaurus, a medium sized North and Central American sauropod, in 1990 by John Stanton McIntosh; meaning he was renaming Saltasaurus australis. One interested more in the phylogeny of Neuquensaurus should check out this more modern article by Salgado, et al. that describes a new specimen of the dinosaur discovered in Northern Patagonia. More specific descriptions of systems of the dinosaur have also been researched, studied, and published as well. These include the appendicular skeleton (Otero 2010), hindlimb attributes (Otero 2008), and vertebral diversity (Zurriaguz 2016).

23 January 2017

Movie Time

Neuquensaurus is not as famous as its cousin Titanosaurus. There is no problem with that of course. It does result in fewer documentaries and other instances of fame for the slightly smaller Neuquensaurus though. We did see a video yesterday of our sauropod, and it did contain a good set of facts and relevant illustrations, which is sometimes all one receives in a documentary of a given dinosaur. Instead, we have a few short videos that we could potentially look at this evening, but I think only one of them is really worth the time (it is also the only video that is not made with toys or only slightly on topic). This video shows a mounted skeleton from the Azara Foundation of Natural History. The mount is featured on the foundation's website as well. Despite not relating any facts or the story of the mount, the short up close perusal of the skeleton is wonderful and the work put into the posture and look of the skeleton is well thought out and done with care; very important aspects of recreating lifelike postures of fossil animals, in my opinion.

22 January 2017

A Video for the Day

Neuquensaurus is becoming more well-known now that it has been accepted into the literature and its history well established. There are numerous websites that have facts and and lists of facts about the dinosaur. However, in the interest of brevity, I would like to post a WizScience video that summarizes the majority of these websites in a single medium:

21 January 2017

A Neu Saurus

A number of Argentinian sauropods, and sauropods world-wide for that matter, are known from fragmentary limbs, vertebrae, or a combination of the two. One such sauropod group of Argentina is the renamed Titanosaurus genus now known as Neuquensaurus. Possessing a femur that is "only" 0.75 m (2 ft) long, Neuquensaurus is a small sauropod and a miniscule titanosaur. However, it is also one of the most well documented and preserved of the Argentinian sauropods to date. the nomenclatural history of this dinosaur is complex and we will suss out the history of it sometime this week, but needless to say, it is a history with many twists, turns, and changes.
©Ezequiel Vera

20 January 2017

Koolasuchus Looks Like A Salamander

Almost all of the image of Koolasuchus that one finds online make the animal look like nothing more than a enlarged ancient salamander trudging about in the swamps and rivers of the Cretaceous of Australia. The illustrations and graphics of Koolasuchus are almost always very dark as well, which may make a lot of sense for a crocodilian-like animal employing ambush tactics from underwater to hunt. A high number of images also make use of bright yellow and orange colors on Koolasuchus. Some salamanders do indeed possess these bright colors, so the realistic application to extant taxa that are similar is acceptable. Koolasuchus may have, being hypothesized as an ambush predator, slightly less likely to be a successful predator if their prey was capable of seeing them from a distance. Either way, there are a number of great illustrations to choose from to share today. The most dynamic of these images, however, shows a pair of the giant animals swimming in relatively calm, deep waters. A third swims through the background in the darker waters of the lake or river. The contrails of the moving limbs make the animals appear even more dynamic as they dive and surface and swim about their habitat. In this image we see that there is potential for these animals to be a lot more active and interesting than typically portrayed.
©Jacek Major

18 January 2017

Koolasuchus Anatomy

Koolasuchus cleelandi was approximately 5 m (16 ft) long and 500 kg (1100 lbs). The large temnospondyl had an enormous head measuring about 65 cm (26 in) from snout to occiput. That head has been described a number o different ways, but it is most commonly depicted as possessing caudal facing lateral horns or as possessing a completely rounded head, like most modern salamanders. That enormous head was common in the Cretaceous rift valleys of Australia within the Arctic Circle. At that time Koolasuchus and its environment was subject to the long dark seasons of the extreme southern end of Earth. Koolasuchus and the dinosaurs it lived with were well adapted for these seasonal changes in different way. Though a hypothetical situation has been posed for this environment, the hibernation of Koolasuchus is based on similar cycles of extant salamanders. The fast moving streams in which Koolasuchus lived were ideal for crocodilian type predators, as Koolasuchus was hypothesized to have been. Unfortunately, its crocodile-like habits most likely led to its displacement and extinction as crocodilians, better at being crocodilians, took over their waterways and out competed Koolasuchus, replacing it in younger geographic strata.

17 January 2017

Reading About Temnospondyls

Temnospondyls have not been discussed much here, as a group. Therefore, we do not have a vast library of literature concerning them that I can point back at and say "remember when we read such and such" making papers regarding Koolasuchus cleelandi that much more unique and special for us this week. One of the problems of Koolasuchus being a largely ignored taxon though is that there is not a lot of literature to fall back on. There are plenty of papers that mention or compare the animal to other closely related animals, but few that investigate the biology or history of Koolasuchus itself. The remains of Koolasuchus are actually fairly substantial (portions of the mandible plus an assortment of post-cranial elements) compared to many fossils and lacking elements cannot be blamed in this instance. Subsequent discoveries of Koolasuchus fossils have added even more material to the known animal, further alleviating lack of information issues. However, given that the papers linked above refer to Koolasuchus but are not entirely dedicated to the temnospondyl, the paper to read this week for the most information on the animal is the description paper of Warren, et al. 1997 that describes the discovered elements in detail. An extensive paper, the anatomy is discussed at length and placement of the animal is also discussed, though Warren and Marsicano 1999 reexamines the phylogeny of Brachyopoidea which discusses the placement of Koolasuchus and many other temnospondyls.

16 January 2017

Walking with Temnospondyls

Koolasuchus appears in one Walking with Dinosaurs episode and in no other documentaries, movies, or cartoons. It is kind of a dud in terms of animation/CGI. Koolasuchus is not the problem though, public interest and knowledge prior to the inclusion of the large temnospondyl in this episode. Koolasuchus figures into the episode significantly and it was well received in the episode. Enjoy this short clip of the temnospondyl trudging about the Antarctic forest (ignore the title please):

15 January 2017

Kool's Crocodile

There are fact pages all over the internet for Koolasuchus. Part of the reason that the BBC, Cool Dino Facts, the Walking with Wikia have dedicated pages to this salamander-like animal is because of it role in the Walking with Dinosaurs series. Koolasuchus is a feature animal in an episode of the series, but this has allowed the animal to become more well-known (outside of the fossil amphibian research circles). This video discusses the animal and some of what we know about the animal, most of which is covered in the fact pages, but includes multiple visualizations as well, which can be helpful.

14 January 2017

Curiousity Piqued

The Cretaceous amphibian Koolasuchus was not at all a suchian (crocodilian) but it was fairly cool; though it was named for Lesley Kool, not because it was interesting. Evoking the very image of the modern salamanders, Koolasuchus was a member of the temnospondyl group; a large group of tetrapods often considered the most primitive amphibians. Tenospondyls were often mostly aquatic and, while this does not entirely separate them from modern amphibians (think of all f the entirely aquatic amphibians that are still around us today), it was a defining characteristic of many temnospondyls. What does an "entirely aquatic" fossil animal look like though? In the case of Koolsuchus that body type is dorsoventrally flattened and very salamander-like. What I mean by that term is an elongate, smoothed body with somewhat shortened limbs and a tail that, in some instances, is mediolaterally thin and dorsoventrally wide; this aids the salamander in swimming around its environment. Salamanders that are not as aquatic, including some newts, have more conical tails. As we said previously, Koolasuchus was an aquatic animal, making the thin tall tail more realistic.
©Peter Trusler for Museum Victoria of Australia

13 January 2017

The Sapeornis Image We Know

Matt Martyniuk's Sapeornis looks a bit like a hawk or a falcon. Jeff Powers also went with that look for Sapeornis. The exact look of the bird is actually unknown, but that is a good start. Many other illustrations have shown the bird as a sparrow-esque or corvid-like (think ravens and crows) animal. Regardless of how the bird is envisioned, artists have done wonderful things with the look of the bird. Not all of the illustrations are magnificently and brilliantly colored, but as of yet we do not know what the coloration of Sapeornis may have been. Michael Rothman's illustration is one of those that is less colorful; however, it is still a beautiful piece and it exhibits an amazing  representation of the tail feathers that were discussed the other day.

12 January 2017

Putting the SAPE in it

Sapeornis is named after the Society of Avian Paleontology and Evolution (SAPE), but what is that exactly? SAPE is an organization of scientists devoted to researching the origins and adaptations of birds from the Mesozoic to the modern era. The group is actually somewhat small, by typical scientific society standards, but is populated by an eager and able group of researchers. Their dedication to describing and discovering fossil birds and their course through history has earned the society a great deal of notice in scientific circles and their achievements were rightfully honored with the naming of Sapeornis. This is not the only claim to fame or public notoriety associated with the bird, however. Despite the dearth of movies, documentaries, and gaming references (very typical outlets for dinosaurs and other fossil animals in the public domain), Sapeornis is a fairly well-known fossil animal. Unfortunately, it is often lumped into lists of fossil birds, which is how it is well-known by the public. It is an average sized bird, by today's standards, which is interesting, but does not make it terribly popular by any means.
©Matt Martyniuk

11 January 2017

Losing Your Tail

Sapeornis was one of the first primitive birds lacking a bony tail. Ancestors to this and some other primitive birds still possessed bony elongate tails. The newer crop of birds had evolved shorter, more derived (and "modern") tails consisting of a pygostyle and retrices attached to the this feature. The pygostyle of modern birds is composed of variably curved fused caudal vertebrae on which specialized tail feathers, called retrices, attach. These tail feathers can be stiff and supportive like in woodpeckers, long and showy as in some hummingbirds, or agile and utilitarian like those seen in hawks and other soaring birds. There is a spectrum of other varieties within this diversity as well. Sapeornis possessed an intermediate pygostyle that was still longer than the modern equivalents but was very rod-like. As of now there is no evidence of the tail feathers, however they undoubtedly existed in some form, as seen in this illustration:
©Yike Xu

10 January 2017

Papers of Today

Yesterday suffered from a lack of movies. Articles and scholarly papers, though, are another story. As with many fossil birds and new species that defy even the smallest portion of our perceived established knowledge there is a great deal of research conducted to determine where and how that fossil fits into the history of life. Sapeornis is no different. There are papers that describe the anatomy of Sapeornis (namely the original naming and describing article), individual species of the genus, and differences across life history. The most interesting paper, to me of course, that the search turns up is discussing the lack of key sternal elements that birds use to achieve powered flight. Zheng et al. 2014 discusses Anchiornis in addition to Sapeornis but the most important set of facts here is that these two genera from China are lacking elements considered to be of particular importance to flight. The abstract is written such that it sounds as though these animals entirely lack a sternum, which seems somewhat unlikely. The paper, however reveals that this feature was not so much absent as it was not ossified, instead existing as a cartilaginous structure in the most primitive birds and their closest dinosaur ancestors.

08 January 2017

A Fun Little Bird

Fossil birds have a habit of becoming popular overnight. This is in part because we have so few good fossil birds that any that are well preserved are sensational. However, Sapeornis is somewhat of a fossil celebrity and because of this there are many sites online that discuss, disseminate, and describe the facts thaat we know about this small fossil bird. The first site is one we are very familiar with here, Prehistoric Wildlife, which presents facts at a reasonable reading level and includes suggestions for continued reading at the end of the passage. The KidzSearch encyclopedia also has a page on Sapeornis, though this page is significantly shorter than that of Prehistoric Wildlife. Still, it does manage to cover some of the most important facts that we know about this animal, which is what is important in a fact page. Lastly, a much shorter reading experience can be had at the Dinopedia (it is literally only three sentences) along with a very nice illustration of a rather colorful representation of Sapeornis.

07 January 2017

Talking About Birds

This week, because last week contained National Bird Day, we are going to discuss a well-known fossil bird that we have not yet discussed. Described and named in 2002 by Zhou and Zhang, Sapeornis chaoyangensis is a 30cm long Chinese fossil named after the Society of Avian Paleontology and Evolution. Still sporting a mouth full of teeth, Sapeornis was a primitive bird with many characters and appears to bridge the evolutionary gap to birds in that some are dinosaurian, some avian, and some clearly show evolutionary development between the two. A number of Chinese bird fossils found after Sapeornis have been synonimized with Sapeornis, meaning that there are a lot of differently preserved specimens of Sapeornis. This also means that we have a more complete image of Sapeornis than was understood when the bird was originally discovered. 
Hong Kong Science Museum display (photo by I, Laikayiu)

06 January 2017

Beautiful Sloths

It is difficult to find a quality and beautiful image of a sloth. There are two typical poses for Megatherium in illustrations; 1) Rearing up and eating from a tree and 2) Walking toward or around a tree on all fours. Of these two types of illustrative motif, about half involve an elongate serpentine sloth tongue wrapping around leaves; there are even sculptures with their tongues out for no clear reason. Approximately a quarter of all of the illustrations remaining (i.e. sans tongue) are actually posed skeletal drawings. Finding an exquisitely drawn and original composition of this type is actually quite difficult, truth be told; there are plenty of well drawn images of course. I have managed to find one image that is both very well drawn and strangely unique. There is no mention anywhere, that I have seen, of a swimming Megatherium, but there is a chance that these sloths would have encountered water and had to cross it. They may not have submerged themselves this much necessarily, but a submerged swimming sloth is an interesting idea and the job done here in portraying a wet furry mammal is well executed. The animal portrayed is actually incorrectly labeled Megatherium in a few spots online and is actually a member of a closely related family of semi-aquatic sloths known as Thalassocnus sloths, but they are similar enough to Megatherium that the imagery is appropriate though slightly inaccurate.
©Diego Barletta

05 January 2017

Famed Sloths

One wondering just how famous Megatherium is need look no further than all of the evidence that has been intermittently presented this week. The different outlets for popular culture are actually more extensive for these giant sloths than for many much more famous dinosaurs that we know and love. Possibly one of the best unshared videos and sources of entertainment this week is this lovable commercial from Nissin, the company that produces Cup Noodles:

04 January 2017

The Bass on the Plain

Case in point al a ©Dmitry Bogdanov
It is not at all difficult to imagine Megatherium as an immense animal with a sizable body and a stout hindquarters; we see it sitting on its haunches often enough in the illustrations and animations that are produced featuring the animal. Megatherium was very likely covered in a thick shaggy fur coat, like its modern day relatives, and possessed rather interestingly curved forefeet and hindfeet sporting enormous claws. These claws forced the forefeet into their unique configuration because it was impossible for the sloth to bear weight on the claws without breaking them and injuring its digits, hands, and wrists. The tails of these sloths were much more substantial than their modern relatives, though they appear to be more readily able to bear the weight of the animal when on two legs and reaching for higher branches in the trees from which it is feeding.

Most of the illustrations of these animals are dark brown or black in color; however, they are often shown reaching up into solitary trees on the plains or at the edge of a forest with their backs to the plains. Undoubtedly a terrible plan as those plains were often filled with saber tooth cats, wolves, and bears. Living in groups, rather than in solitude, may have made this coloration issue less dangerous for the sloths as well. At the edge of a forest this coloration makes sense as anything looking at a giant brown animal might lose it in the dark background of a heavy forest. At a solitary tree in a savannah, however, this becomes a different story. Coloration can be justified by the history of the genus; which may have had members on South American plains as well. Many of the species of Megatherium were indigenous to South America and, covered in forest or rain forest, South America had many trees, making darker coloration more realistic.

03 January 2017

Slowly Writing Slow Creatures

Megatherium was one of the most well-known descriptions published by Georges Cuvier at the end of the 18th century. A number of papers were published and read in the following 60 years by Richard Owen that described the animal in even more detail and were possibly even more important to future studies of the animal than the initial descriptions. Owen released these partial descriptions as they were read to the Royal Society in London during the 1850's, though their official dates for publication often preceded the readings by a few months. Owen produced this description both as a five part series of lectures and later as a memoir containing eleven parts.

Owen and Cuvier are not the only scientists that have shown interest in Megatherium. More recent research has been conducted on the giant sloths as well, including some biomechanical studies that reveal details about the capabilities of the giant sloth to bite and how the shape of its skull influences the forces it can generate and dissipate. There is, as we expect with mammals, a body of work discussing the teeth of ground sloths in addition to the biomechanical work mentioned above. Teeth and bite force obviously can be related and mammalian teeth are regularly discovered, so this is not an unusual study by any means.

02 January 2017

Television and Movie Stars

Megatherium has appeared in a number of television and movie roles. It is typically portrayed as a slow animal about to be eaten; this is not always entirely wrong. However, one episode of Walking With Beasts discussed the animal, though briefly, as a well defended animal. This implies that it may have also been able of killing predators that attacked it.
Not all documentaries are as kind to the ground sloths and, as we have probably all seen, the internet and documentary viewing people of the world always seem to want to know what animal could beat what other animal. Due to this phenomenon there are, of course, videos that show the ground sloths fighting other contemporaneous mammals (and there are probably some links online somewhere showing it fighting dinosaurs because it is the internet). The most recent of these types of videos depicts the hypothetical clash between Megatherium and a short-faced bear (Arctodus). The reconstruction is actually a little funny, but it also represents a viable series of hypotheses that a lot of people find very compelling.

01 January 2017

Ground Sloth Fact Files

Megatherium is a well-known genus of the ground sloths and as such has a dedicated following of professional and amateur fossil enthusiasts willing to write and share information about the large mammals in easy to read webpages for all ages to learn more about Megatherium. The best sites from the front page for facts about Megatherium include:

1) About - The site discusses not only Megatherium but another well-known ground sloth, Megalonyx and talks discusses the contemporary landscape. This page is suited to higher elementary or middle school readers.

2) Your Kids Planet - A site with higher level paragraphs describing and discussing Megatherium and many of the other facts covered in the About website.

3) Mentalfloss - A list of ten facts is presented for readers at a comfortable reading level that is intermediate between the first two links. There are some challenging words in the paragraphs, but not so challenging that they should stop younger readers completely.

4) Extinct Animal Facts - Presented as quick sentences, this list of facts is easily readable but does lump all ground sloths together, mixing facts here and there.