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Hatzegopteryx thambema
#1
Hatzegopteryx thambema

[Image: hatzegopteryx_1.jpg]

Temporal range: Late Cretaceous, 65 Ma

Kingdom: Animalia 
Phylum: Chordata 
Order: †Pterosauria 
Suborder: †Pterodactyloidea 
Family: †Azhdarchidae 
Genus: †Hatzegopteryx Buffetaut, Grigorescu & Csiki, 2002 

Hatzegopteryx ("Hațeg basin wing") is a genus of azhdarchid pterosaur, known from incomplete remains found in Transylvania, Romania. The skull fragments, left humerus, and other fossilized remains indicate it was among the largest pterosaurs. The skeleton of Hatzegopteryx has been considered identical to the known remains of Quetzalcoatlus nothropiQ. northropi has not yet been properly described, and if it is not a nomen dubiumHatzegopteryx is possibly its junior synonym.

Naming and fossils
The genus was named in 2002 by French paleontologist Eric Buffetaut, and Romanian paleontologists Dan Grigorescu and Zoltan Csiki. It is known from only the type species, Hatzegopteryx thambema. The generic name is derived from the Hatzeg (or Hațeg) basin of Transylvania, the so-called Hațeg Island, where the bones were found, and from Greek pteryx, or 'wing'. The specific name thambema is derived from the Greek for 'monster', in reference to its huge size.

Hatzegopteryx hails from the Densuș-Ciula Formation of western Romania, which has been dated to the late Maastrichtian stage of the late Cretaceous Period, around 65 million years ago. The holotype, FGGUB R 1083A, consists of the back part of the skull and the damaged proximal part of a left humerus. A 38.5 centimeter long middle section of a femur found nearby, FGGUB R1625, may also have belonged to Hatzegopteryx.

Skull
Hatzegopteryx apparently had a robust skull broadened in the rear, and a massive jaw. Its lower jaw featured a unique groove in its point of articulation, also seen in some other pterosaurs, that would have allowed the animal to achieve a very wide gape. Many of the fossilized bones of Hatzegopteryx resemble those of the closely related Quetzalcoatlus sp., though in Hatzegopteryx the skull was much more heavily built, and had a markedly different jaw articulation, similar to that seen in Pteranodon. Based on comparisons with other pterosaurs, Nyctosaurus and Anhanguera, Buffetaut and colleagues when initially describing the specimens estimated that the skull of Hatzegopteryx was probably almost three meters (ten feet) in length, which would have made it larger than that of the largest Quetzalcoatlus species and among the largest skulls of any known non-marine animals.

The skull of Hatzegopteryx was also unique in its heavy, robust construction. Most pterosaur skulls are made up of very lightweight plates and struts. In Hatzegopteryx, the skull bones are stout and robust, with large-ridged muscle insertion areas. In their 2002 description, Buffetaut and colleagues suggested that in order to fly, the skull weight of this pterosaur must have been reduced in some unconventional way (while they allowed that it could have been flightless, they found this unlikely due to the similarity of its wing bones to flying pterosaurs). The authors theorized that the necessary weight reduction was accomplished by the internal structure of the skull bones, which were full of small pits and hollows (alveoli) up to 10 mm long, separated by a matrix of incredibly thin bony struts (trabeculae), a feature also found in some parts of Hatzegopteryx wing bones. The authors pointed out that this unusual construction, which differed significantly from the irregular internal structure of other pterosaur skulls, resembles the structure of expanded polystyrene, the substance used to make Styrofoam. They noted that this would allow a sturdy, stress-resistant construction while remaining lightweight, and would have allowed the huge-headed animal to fly.

Size
The authors estimated the size of Hatzegopteryx by comparing the humerus fragment, 236 mm (9.3 in) long, with that of Quetzalcoatlus, of which specimen TMM 41450-3 has a 544 mm (1 ft 9.4 in) long humerus. Observing that the Hatzegopteryx fragment presented less than half of the original bone, they established that it could possibly have been "slightly longer" than that of Quetzalcoatlus. They noted that the wing span of the latter had in 1981 been estimated at eleven to twelve metres, while earlier estimates had strongly exceeded this at fifteen to twenty metres. From this they concluded that an estimate of a twelve meter wing span for Hatzegopteryx was conservative "if its humerus was indeed somewhat longer than that of Q. northropi". In 2003 they moderated the estimates to a close to twelve metres wing span and an over 2.5 m (8 ft 2 in) skull length. In 2010 Mark Witton e.a. stated that any appearance that the Hatzegopteryx humerus was bigger than TMM 41450-3 had been caused by a distortion of the bone after deposition and that the species thus likely had no larger wingspan than Quetzalcoatlus, today generally estimated at ten to eleven metres.

[Image: Hatzegopteryx.jpg]
[Image: wildcat10-CougarHuntingDeer.jpg]
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  • Claudiu Constantin Nicolaescu
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#2
Giant flying reptile was top predator like a winged T. rex

[Image: hatzapocalypse.jpg]
Winging it: dwarf dinos were tasty morsel for giant winged reptile
CC BY-SA 4.0

Old horror movies such as the 1925 The Lost World might have got it right after all. They portrayed pterosaurs as giant terrors of the skies, flying reptiles who snacked on large prey — and would in theory be dangerous even to humans.

Scientists have instead come to think most pterosaurs were more like overgrown cranes that caught rat-sized baby dinosaurs on the ground and swallowed them whole.

New fossils now indicate some giant pterosaurs probably did dine on bigger prey, such as dwarf dinosaurs the size of a small horse, 70 million years ago on an island that became modern-day Transylvania.

Pterosaurs grew huge in the late Cretaceous, most famously Quetzalcoatlus northropi with a 10 to 12-metre wingspan, known from a Texas fossil.

The giants belonged to a family called azhdarchids, which shared a common body plan, with long thin wings and necks, and lightly built bodies and heads. Most fossils are fragmentary and scrappy.

Massive neck

But the Romanian fossils show that the little known Hatzegopteryx had a short and massive neck, much stronger than those of other known azhdarchids.

Darren Naish at the University of Southampton and Mark Witton at Portsmouth University, both UK, describe an exceptionally broad neck bone with walls 4 to 6 millimetres thick, triple those of other azhdarchids, and a spongy filling that makes them very strong.

“The bones we are taking out of Romania show a much more robust and massive animal than we previously imagined,” says Witton. “We assume the whole pterosaur is stocky and powerful.”

This would have made it extremely dangerous, with a mouth wide enough to swallow a small human or a child. Earlier studies showed that Hatzegopteryx had a jaw that at about half a metre wide, was unusual for the narrow-bodied azhdarchids.

Tethys Sea

The fossils come from Hateg Island, a large part of modern Romania which at the time sat in the Tethys Sea. The giant pterosaur shared the island with dwarf dinosaurs, including long-necked sauropods the size of horses.

A century of digging found no teeth from giant predatory dinosaurs, a sign that pterosaurs were the biggest and baddest predators on the island. With throats and jaws much wider than other pterosaurs, they could have swallowed small dinosaurs whole.

“With a little distension of their throats, those things could swallow small humans very well,” Witton adds. If the quarter-tonne Hatzegopterxy was the biggest predator on the island, it wouldn’t have to worry about flying to a safe place with a belly-full of dinner.

An ecosystem with small dinosaurs being hunted by giant pterosaurs may seem “kind of strange,” says Mathew Webel at the Western University of Health Sciences in Pomona, California. But he says it makes sense because modern islands also produce strange ecosystems.

https://www.newscientist.com/article/2119323-giant-flying-reptile-was-top-predator-like-a-winged-t-rex/




Journal reference:
Naish D, Witton MP. (2017) Neck biomechanics indicate that giant Transylvanian azhdarchid pterosaurs were short-necked arch predators. PeerJ 5:e2908 https://doi.org/10.7717/peerj.2908

Abstract
Azhdarchid pterosaurs include the largest animals to ever take to the skies with some species exceeding 10 metres in wingspan and 220 kg in mass. Associated skeletons show that azhdarchids were long-necked, long-jawed predators that combined a wing planform suited for soaring with limb adaptations indicative of quadrupedal terrestrial foraging. The postcranial proportions of the group have been regarded as uniform overall, irrespective of their overall size, notwithstanding suggestions that minor variation may have been present. Here, we discuss a recently discovered giant azhdarchid neck vertebra referable to Hatzegopteryx from the Maastrichtian Sebeş Formation of the Transylvanian Basin, Romania, which shows how some azhdarchids departed markedly from conventional views on their proportions. This vertebra, which we consider a cervical VII, is 240 mm long as preserved and almost as wide. Among azhdarchid cervicals, it is remarkable for the thickness of its cortex (4–6 mm along its ventral wall) and robust proportions. By comparing its dimensions to other giant azhdarchid cervicals and to the more completely known necks of smaller taxa, we argue that Hatzegopteryx had a proportionally short, stocky neck highly resistant to torsion and compression. This specimen is one of several hinting at greater disparity within Azhdarchidae than previously considered, but is the first to demonstrate such proportional differences within giant taxa. On the assumption that other aspects of Hatzegopteryx functional anatomy were similar to those of other azhdarchids, and with reference to the absence of large terrestrial predators in the Maastrichtian of Transylvania, we suggest that this pterosaur played a dominant predatory role among the unusual palaeofauna of ancient Haţeg.

[Image: fig-6-2x.jpg]
Figure 6: Speculative skeletal reconstructions of Hatzegopteryx sp. and Arambourgiania philadelphiae (estimated wingspans ≥10 m—Frey & Martill, 1996; Buffetaut, Grigorescu & Csiki, 2003) to show discrepancy in neck length alongside a ‘typical’ azhdarchid body plan.
(A) Hatzegopteryx skeleton in lateral aspect; (B) dorsal view of EME 315 and FGGUB R1083 jaw elements, proportionate to actual size, suggesting Hatzegopteryx bore a wide, as well as relatively short, neck construction (soft-tissue outline in black). Jaw width after Buffetaut, Grigorescu & Csiki (2003); © reconstructed Arambourgiania philadelphiae cervicals III–VII in lateral aspect; (D) 4.6 m wingspan Q. sp. skeleton in lateral aspect; (E) Q. sp. cervical vertebrae III–V and skull in dorsal view; Note how the neck length of Hatzegopteryx is similar to this much smaller pterosaur. H. thambema holotype (FGGUB R1083) and undescribed referred elements are shown in (A); known elements of A. philadelphiae (UJA JF1) indicated in white shading in ©. Scale bar represents 1 m.

Full PDF : Neck biomechanics indicate that giant Transylvanian azhdarchid pterosaurs were short-necked arch predators.
[Image: wildcat10-CougarHuntingDeer.jpg]
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  • Claudiu Constantin Nicolaescu
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#3
I decided to start drawing realistic dragons and I thought that first I should probably make a short study on giant pterosaurs.

Here is my study on Hatzegopteryx. I estimated its total wing area at approximately 11 m^2. Assuming a mass of 250 kg. this means it had a wing loading of 22 kg/m^2, which is probably about as much as the heaviest flying birds. Should we assume that these giant pterosaurs were incapable of soaring?

[Image: 20181109-153841.jpg]
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#4
(11-10-2018, 12:18 AM)Thalassophoneus Wrote: I decided to start drawing realistic dragons and I thought that first I should probably make a short study on giant pterosaurs.

Here is my study on Hatzegopteryx. I estimated its total wing area at approximately 11 m^2. Assuming a mass of 250 kg. this means it had a wing loading of 22 kg/m^2, which is probably about as much as the heaviest flying birds. Should we assume that these giant pterosaurs were incapable of soaring?

[Image: 20181109-153841.jpg]

That doesn't look like a very stable animal. How good would it have been at getting around on land?

Edit: I know pterosaurs were at least somewhat capable of traveling on land, but there is just something abut that pic that screams ''unstable'' to me. Am I overlooking something, Thalassophoneus?
Mmm, chocolate cake
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  • Claudiu Constantin Nicolaescu
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#5
These are the usual proportions of azhdarchids. Maybe what makes it look kinda "front heavy" is the slanted neck. But I think this is more accurate than being vertical.
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#6
(11-10-2018, 07:03 AM)Thalassophoneus Wrote: These are the usual proportions of azhdarchids.
Oh Jesus, walking must have been very hard, then!


Back on topic, I do not doubt that it is more accurate, but WHY exactly would one favor a forward-slanting pterosaur over one standing up straight?
Mmm, chocolate cake
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#7
Actually azhdarchids must have been pretty agile on the ground thanks to their long legs.

In the case of the above drawing I made the inclination of the back and then continued to the neck, which is straight and curves very little upward. It would have to bend its neck to an "S" shape to look more vertical, but this must have been pretty hard for Hatzegopteryx since it had few cervical vertebrae.
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