Falcarius (Falcarius): dinosaurs from the Terizinosaurid family

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Falcarius (lat.: Falcarius) is a genus of dinosaurs from the Therizinosauridae family of the Theropoda suborder. The remains of a member of this genus were found in the Cretaceous deposits in the center of Eastern Utah, USA. Falcarius was a “bipedal”, supposedly omnivorous dinosaur, whose body length was 4 meters. It had a small head and a long neck and tail.

A 2005 description of the Falkaria, following the 1999 description of the therizinosauroid Beipiaosaurus (lat.: Beipiaosaurus), which lived on the territory of modern China in the Lower Cretaceous period, explains the early evolution of representatives of the infrast detachment Terizinosauria (Theerizinosauria) and their kinship with a wider group the submarine of theeropoda (Theroopoda), since the falkaria is a transitional form from which are more ancient teenic. to terizinosaurids that has undergone significant evolutionary changes.

Discovery history

The remains of this dinosaur were first discovered in 1999 by fossil collector Lawrence Walker.: Lawrence Walker) in the Crystal Geyser Quarry Quarry in Grand County, Utah, USA. He reported his find to paleontologist James Kirkland.: James Kirkland), who since 2001, along with a team from the Utah Geological Survey, has occasionally found bones in the Cedar Mountain Formation in an area of ​​8,000 sq. m.

Thus, Falkaria lived in the Lower Cretaceous period (in the Barremian stage) about 126 million years ago. 2 extensive bone aggregations have been discovered, including the fossilized remains of hundreds, perhaps thousands, of dinosaurs belonging to an unknown new genus. In 2006, scientists estimated their number at least 300 copies.

In 2005, the remains of more than 2 thousand individuals were extracted from the ground, in most cases consisting of incredible bones. Among the bone material found, skeletons of young animals were present.

In 2008, a message appeared about the discovery of another cemetery of these dinosaurs in the career of Suarez-Koori (English.: Suarez quarry), consisting of the remains of mainly adults, but perhaps a slightly different species.

In 2010, the number of individuals found in the first career exceeded 2700, and later it was already reported about more than 3 thousand copies found.

The story of the name

When the first scientific report on Falkaria was published in 2004, which followed a partial description of its cranial box and the appendicular skeleton of the upper body, the dinosaur formally remained unnamed before the publication of the rereport in the May issue of the general scientific journal “Nature” (English.: Nature) for 2005.

A well-known quote from one of the co-authors of the study, Dr. Scott Sampson (Eng.: Scott Sampson), who said that the genus “…is the missing link between carnivorous dinosaurs and bizarre herbivorous therizinosaurs”.

Later Lindsey Zanno.: Lindsay Zanno) informally described this dinosaur as “a highly bizarre creature: a cross between an African ostrich, a gorilla and the protagonist of the science fiction film Edward Scissorhands” (Edward Scissorhands).

The type species of Falcaria is Falcarius utahensis. The Latin generic name “Falcarius” means “reaper” and indicates the presence of long sickle-shaped claws on the forelimbs of this theropod. The specific epithet “utahensis” specifies that we are talking about a species from Utah.

Description

The falkarii holotype no. UMNH VP 15000 is represented by a fragmentary skull. More than 660 paratypes have been assigned to the species Falcarius utahensis. In addition to the skeletons of this vast hypodigm (t.e. groups of individuals) belonging to representatives of this species was also attributed to dozens of other bones found.

On June 29, 2005, the Utah Museum of Natural History opened an exhibition of the reconstruction of the skeleton of this dinosaur, made by Gaston Design from cast elements.

Body dimensions

After examining the fossilized remains of several individuals, scientists found that the average body length of representatives of the Falcarius utahensis species was 3.7-4.0 meters, and the height was slightly more than 1.2 meters. In 2010, paleontologist Gregory Scott Paul.: Gregory Scott Paul) estimated the body weight of this dinosaur at 100 kilograms. The body length of the smallest juveniles did not exceed half a meter.

Distinguishing anatomical features

In 2010, Lindsey Zanno identified several autapomorphies in Falkarii, that is, unique derivatives of anatomical features. So, on the underside of his skull there is a clearly defined depression, the basisphenoid sinus.

In the back of the skull, in particular under the occipital condyles, there are deep depressions, each with several air grooves. The relief point of attachment of the extensor tendon on the claw of the thumb of the hand of the upper limb is limited by deep grooves for ligaments.

Large openings in the nasal part of the skull (preorbital fenestrae), located in depressions reaching the lateral edges of the nasal bone. The anterior part of the lower jaw of a Falkaria contains at least 5 pairs of conical teeth. These teeth are notched on the inside.

The underside of the cervical vertebrae has a depression with a ridge along the midline. Under the anterior outgrowths of the dorsal vertebrae (anterior articular processes) there is a groove divided into 3 recesses of smaller length.

The middle dorsal vertebrae have a second ridge running from the bases of the joints of the upper ribs (diapophyses) to the back of these vertebrae. The body of the shoulder bone of the upper limb of the dinosaur is enhanced by powerful, slightly inclined thickenings aimed to condyles in the elbow joint.

Skeleton

Information about the shape and structure of the head of Falkaria is still very incomplete. It is known that she was small and elongated. Apparently, thanks to its long neck, the dinosaur was able to reach the leaves of trees or to fruits that grew up at an altitude of about 1.5 meters above the ground.

There were at least 16 teeth in the upper jaw of Falkaria. There were 28 in the lower jaw. Small, leafshaped teeth of the upper jaw, the edges of which had very small zabins, indicate that the dinosaur ate plants. At the same time, the 5 front teeth of the lower jaw are much longer, straighter and sharper than the others, which may indicate a partially omnivorous type of food for falcaria, including the consumption of meat from small animals, such as lizards.

The back of the dinosaur’s skull was relatively large. Its lower parts were moderately filled with air-carrying loose bone tissue. What is the length of the individual parts (sections) of the spinal column is not yet known. However, the animal’s neck was very long, with elongated cervical vertebrae. The tail was also relatively long.

The forelimbs were of moderate length, although the humerus was slightly bulky. The relatively large and slightly curved sharp claws of the fingers of the forelimbs of the dinosaur had a length of 10 to 13 centimeters and were probably used by him for self-defense.

Falcarius is known from numerous bone specimens, including several complete forelimb skeletons. In connection with the primitive position in the evolutionary tree and the relative completeness of the skeleton, it is a suitable taxion for comparison with related groups of dinosaurs and derivatives of taxa.

Scientists know most of the bones of the pectoral girdle and forelimbs of the Falcarius, although the bones of the sternum have not been preserved. At the same time, in most specimens, both the left and right shoulder blades are almost completely preserved.

The scapular bones, which are about 225 mm long, are quite thin and have almost no thickenings. They are arched. The scapula was located relatively high in the skeleton. 2 coracoids are also preserved, however, they are morphologically more different from each other than the shoulder blades. At the same time, the right coracoid was better preserved. Both of them are not particularly enlarged.

The thymus is elongated and narrow, the angle between its ends is 104°. It has a V-shape and is equipped with a small median process in front. On the humerus there is a relatively short deltopectoral crest of a triangular shape.

Very thick rowls indicate that the dinosaur had a powerful muscles. The ulna is slightly bent.

The hand is rather long, but not very thick, with an elongated metacarpus, although the first metacarpal is short. The first finger is located at an angle to the second, longest, finger of the hand. The third finger is very thin. The nails of the fingers are moderately curved, rather pointed and moderately long.

The lower limbs were relatively long and adapted for running, with the tibia being longer than the femur. Dinosaur foot had 3 toes. Another, first, toe did not reach the surface of the earth, and the first metatarsal bone did not touch the tarsus.

Classification

In 2005, the compilers of the description attributed Falkaria as a basal representative to the superfamily Therizinosauroids (lat.: Therizinosauroidea) according to Zhang Fucheng’s classification (pinyin: Zhang Fucheng). Later, Lindsay was boring him as the most basal taxon of the infrast detachment Terizinosaurus, not related to the suprafamily of terizinosauroids according to the classification of Paul Sereen (English.: Paul Sereno.

Falkaria bears a resemblance to dinosaurs from the Therizinosaurid family, which is part of the Maniraptor clade (lat.: Maniraptor). At the same time, he himself, perhaps, does not belong to therizinosaurids, although he is included in the more extensive infraorder Therizinosaurs.

Representatives of this infraorder are characterized by wider hips, a relatively large skull and a long neck, typical of herbivorous dinosaurs. Evolutionarily more advanced Asian therizinosaurs were covered in goose-like feathers. It is assumed that the falcarius also had plumage. In general, it can be considered as a transitional form between basal theropods and more highly developed therizinosaurids.

Falkaria had a number of signs common with terizinosaurids: it also had a long neck, a small head with teeth adapted for eating plant foods, more powerful upper limbs with large claws, in addition, it, like terizinosaurus, also had a less inclined body position.

On the other hand, with its long tail, long legs and feet with a fourth finger that did not reach the surface of the earth, it looked like more typical theropods.

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