Scientific Illustration

lostbeasts:

Rhoetosaurus.
Though the first few fragments of a skeleton were discovered in 1925, the rest of the skeleton was left unearthed until the 1970s. Despite the fact that it skull, hindlimbs and most of its tail are unknown, it remains one of the best known Jurassic sauropods in Australia.

lostbeasts:

Crassigyrinus.
This was a large, completely aquatic Carboniferous hunter, eating the fish and smaller amphibians it shared the water with. It had large teeth and a long sinuous body, with tiny limbs that were useless except for steering whilst swimming.

Also:

twizz-mod:

This is for any of you who were interested in some of the info in my last post: here.

I’ve loved/lived around horses my entire life, and actually already knew some of this. I wasn’t quite sure what each bone was called, but I knew basically where they were located on each creature.

Quite a few of the bones are the same, such as the tibia, humerus, and femur. Others have different names for the same basic part, like the knee of a horse and the wrist of a human.

So basically, on a horse, the “hands and fingers” are from the knee, down. They’re just very….extended. Think of the entire hoof as being the fingernails.

On a pony, the tibia and fibula have to be shorter than on a real horse, but they’re still there, connecting to the hock, which is that “pointy” part on the hind legs.

lostbeasts:

The Paleocene Epoch.
This time period occurred directly after the end-Cretaceous mass extinction event, and was the beginning of the so-called “Age of Mammals”. The supercontinent Gondwana, formed by Australia, Africa, South America and Antarctica was starting to split apart. South America was an island continent, and Europe and Asia were connected to North America, leaving land bridges that enabled early mammals to spread throughout the world.

The global temperature was warmer than it is today, though the 9.5 million year duration of this epoch was much drier than those before and after. Because of these higher temperatures, thick forests grew across the continents, and modern plants, like cacti and palm trees, began to develop.

Because 80% of all life on earth had been destroyed, the mammals and birds remaining found it easy to flourish, evolving relatively quickly to adopt the niches that had been left vacant by the dinosaurs. As a result, a lot of species grew to huge sizes. Birds such as Gastornis evolved as a remarkable shadow of its ancestors, a post-Cretaceous theropod, becoming giant, flightless and predatory. It would have fed upon mammals such as the condylarths.

lostbeasts:

Prodinoceras.
An early member of Dinocerata, Prodinoceras was around the size of a modern tapir, making it one of the biggest animals in Asia during the Paleocene epoch (directly after the end-Cretaceous mass extinction event). It possessed long canines that were protected by flanges on the lower jaw, but didn’t yet have the same bony skull knobs like later uintatheres.

writingcapital:

A third [evolutionary] advance is in a way the most important, since it is the one used by paleontologists to distinguish reptiles from mammals. The lower jaw of reptiles contains several bones, of which two are important to us. One of these, the dentary, bears the teeth while the other, the articular, smaller and at the hind end of the jaw, forms part of the hinge between the lower and upper jaw (Figure 9-8). The other part of this hinge is the quadrate, a small bone in the head portion of the skull, or cranium. Immediately behind these two small jaw bones is the middle ear, within which sound waves are amplified and transmitted from a special nerve to the brain. In reptiles, amphibians, and fishes, this amplification is carried out by a single small bone. By contrast, the lower jaw of mammals consists only of the tooth-bearing (dentary) bone, which is hinged to another bone, the squamosal, also in the cranium. The two bones that form the hinge of the reptilian jaw have not disappeared. They are represented in mammals by two small bones in the middle ear connected with the counterpart of the single reptilian ear bone. In reptiles, amplification of sound waves in the middle ear, carried out by a single bone, is relatively inefficient. The three bones in the mammalian ear do this job much more effectively, so that the hearing of mammals is much better than that of reptiles.

In order to classify fossil animals neatly and clearly as either reptiles or mammals, most paleontologists and nearly all textbooks classify as reptiles all bony-limbed animals that have a liquid-filled amniotic egg and a jaw hinge formed by the two small bones, articular and quadrate, along with a single ear bone. Mammals differ in having the tooth-bearing (dentary) lower jaw bone articulated directly with a bone of the cranium (squamosal), plus three small bones in the middle ear. Tooth structure also helps in classifying them. Nevertheless, an animal that has almost mammalian teeth but a reptilian jaw hinge and middle ear bone is called a reptile. Mammallike reptiles are all classified as reptiles on the basis of this character, even though the advanced dog-tooth has teeth that resemble those of primitive mammals more than they resemble the teeth of the earliest mammallike reptiles or their immediate ancestors, the pelycosaurs. Likewise, the earliest animals having three bones in the middle ear are called mammals, although, like the primitive mammals of modern Australia—the spiny anteater and platypus (monotremes)—they may well have laid eggs, lacked nipples or teats, had skeletons showing some reptilian features such as shoulder girdles, and had chromosomes resembling those of reptiles.

— Stebbins - Darwin to DNA, Molecules to Humanity, pp. 289-91

I find this strangely profound: everyone knows the difference between a reptile and a mammal upon seeing one, but once all the fragile details are stripped away, there’s only a single, trivial difference between them; it’s this one silly little criterion that informs all of our (taxonomical) knowledge about species long-extinct. I suspect that the taxonomies of many disciplines are like this.

The text alongside fig. 9-8 reads:

Figure 9-8.
A series of skulls showing a few of the numerous transitional forms that, via a series of adaptive radiations, resulted eventually in the origin of modern mammals (a)–(c): Three typical reptiles. (a) A primitive Captorhinus that, like early amphibians and modern turtles, has only one pair of openings in the skull in addition to the nostrils. (b) A primitive ancestor of lizards, Youngina. (c) A modern lizard, Varanus. (d)–(i): Six reptiles that were on or near the line leading to mammals. (d) and (e) Two pelycosaurs that were typical reptiles but show the beginnings of tooth differentiation. Note that the hindmost bone of the lower jaw (angular, a) is nearly as large as the tooth-bearing bone (dentary, dn). (f) and (g) Two early mammallike reptiles, showing further tooth differentiation, plus reduction in size of the angular bone. (h) and (i) Two later forms of reptiles that, with respect to tooth differentiation and reduction of the angular bone, were much like mammals. Diarthrognathus was almost completely intermediate between reptiles and mammals. (j)–(l): Three kinds of mammals. (j) Sinoconodon, the earliest of these, still retained a number of reptilian features. (k) A later form, Deltatheridium, was very similar to modern shrews. (l) A modern opossum (Didelphys). The skulls are drawn at different scales of magnification. Those in the center column are at natural size or somewhat reduced; those in the right column are somewhat magnified.

(via lostbeasts)

drfrankscali:

“Want to know how to reduce the pain of a heartbreak? Well, one of the ways is analogous to how you would reduce physical pain: acetaminophen.”

If you like medical facts like this, I please click and “like” my page: www.facebook.com/hackingthehuman

I am a research investigator who has been dissecting cadavers for 7 years. I update daily with facts that I found along my journey.

Cheers,

Dr. S

paleoillustration:

“Triceratops Lane” by Cheung Chung Tat. Triceratops… with poisonous quills? eating meat?.

(…) new Triceratops material revealed its incredible secrets. (…) The result would be an incredibly bizarre-looking, intimidating beast that behaved more like a giant wild boar or an entelodont (a carnivorous pig-like creature) than the placid vegetarian of classic imagery. We simply will never look at Triceratops the same way now. Full article

(via lostbeasts)

lostbeasts:

Jaws of a biting cat compared to a sabretooth cat. Sabretooth cat skulls were designed for a swift downward strike of the sabre-teeth, not a strong bite. The coronoid process was also greatly reduces, meaning the jaws were weakly bound to the skull and couldn’t withstand much bending or twisting.

dino-files:

Name: Euoplocephalus
Pronounced: You-Oh-Plo-Seff-Ah-Luss
Classification: Ornithischian
Sub-family: Ankylosaurid
Temporal Range: Late Cretaceous (70-65 Mya)
Length: 6 metres
Height: 2 metres
Weight: 2,000kg
Movement: Quadrupedal
Feeding Type: Herbivore

Information:
- Discovery: Lawrence Morris Lambe discovered the first specimen of Euoplocephalus in 1902 and named it Stereocephalus; however that name was already preoccupied (it had already been given to a type of insect), so Lambe renamed it, Euoplocephalus in 1910. Although Ankylosaurus is the most famous ankylosaurid dinosaur in popular culture, Euoplocephalus is probably the best known in the palaeontological industry. Researchers have recovered over forty individual Euoplocephalus specimens from Alberta, Canada and Montana, USA. The forty specimens consist of over fifteen known skulls, as well as a few almost-complete specimens with armour plating still attached.

- Statistics: Among the ankylosaurids, Euoplocephalus was exceeded in size only by Tarchia and Ankylosaurus. The wealth of fossil material recovered means researchers have been able to create fairly certain length and weight estimates; with many believing Euoplocephalus would have grown to around 6 metres in length and weighed 2,000kg.

- Description: The skull is the most extensively studied area of Euoplocephalus, and it is wider than it is long. The skull shape gives Euoplocephalus a very broad mouth structure, which suggests it was a generalist browser of low vegetation and possibly had a more advanced, or larger digestive system, to cope with ingestion of a greater variety of plant material. The teeth inside the mouth of Euoplocephalus are small, and like other ankylosaurids are more suitable for chopping.
            Euoplocephalus also has a complex series of nasal passages that are in the snout (an adaptation seen in other ankylosaurid dinosaurs, such as Saichania). Initial explanations for these nasal passages were that they would allow a greater sampling of air, giving Euoplocephalus an increased sense of smell. However, endocasts of the brain suggest this was not the case; instead it seems that the purpose of these passages was to moisten inhaled air. Euoplocephalus itself appears to have been present in ecosystem with dry climates, and having the ability to moisten inhaled dry air would have made these types of climates far more tolerable for Euoplocephalus to live in. In addition, this adaptation would relieve them of respiratory problems as well as reducing the amount of moisture lost during respiration.
            The back and upper flanks of Euoplocephalus were covered in bony armour plates (known as osteoderms). The main osteoderms were arranged in bands that followed one another down the length of the animal; forming armour that was rigid but flexible, so the normal movement of Euoplocephalus was not hindered. In addition to the plates, large spikes rose up vertically from the body; particularly two large spikes rose up from above the shoulders. These spikes would have made it more difficult for large predators to gain a grip on the body with their mouths, reducing the chance of effectively biting through the armour plates. In addition, like with other ankylosaurids, the lower portion of the tail of Euoplocephalus was rigid due to ossified tendons, meaning the tail was only flexible in the upper portion. Combined with the bony club on the end, this would allow Euoplocephalus to swing its tail at other dinosaurs; possibly as a self-defence mechanism for use against predators, or as a weapon used in intra-species combat.

(via lostbeasts)