Paleo File: Deinocheirus

• Name means: “Wonderfully Terrible Hand”
• Height: 3-6 meters
• Weight: 9 tons
• Length: 13 meters
• Region: Gobi Desert, Mongolia

(Copyright: Andrey Atuchin)

         One of arguably the oddest dinosaur discoveries to date, Deinocheirus, has been an enigma for over 50 years. Ever since its discovery Deinocheirus, which translates from Latin to “Terrible Hand”, has captured the imagination of those with the right resources to know about it. Despite its enigmatic nature in the fossil record, Paleontologists were finally able to put the mystery of how the animal looked to rest in 2014.

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         The first fossils of Deinocheirus consisted of the massive forearms (only missing the claws on the right hand), the complete shoulder girdle, three dorsal vertebrae, five ribs, and the gastralia (commonly referred to as belly ribs). Polish Paleontologist, Zofia Kielan-Jaworowska, found these remains in the Nemegt Formation of the Gobi Desert, Mongolia on July ninth 1965. Zofia, along with Paleontologist Rinchen Barsbold, were part of the 1963–1965 Polish-Mongolian paleontological expeditions when they found the remains. The arms were classified as a Theropod dinosaur, and considering the lack of extraneous material, the scientists had no idea as to what the animal looked like until the year 2012. In 2012, Phil R. Bell, Philip J. Currie, and Yuong-Nam Lee issued their findings of new Deinocheirus material. These scientists found more gastralia fossils in the same dig site of the prior team. What they found explained the scarcity of material from the dig site. They found bite marks on the gastralia that matched the teeth of the Tyrannosauid, Tarbosaurus, with which Deinocheirus shared its ecosystem. Then in 2013, Lee, Barsbold, Currie, and colleagues announced the discovery of two new Deinocheirus specimens at the annual Society of Vertebrate Paleontology conference. This find gave great insight into what the animal looked like and where the animal fit in, phylogenetically. Due to fossil poachers, much of the identifiable parts of the skeletons were gone; the heads, feet, and hands were all stolen. A short time later, word of the skull and hands making their way to the fossil black market helped the European museum acquire them. This skull solidified not only the identity of this bizarre dinosaur, but also nailed the final nail in the coffin to the secret of Deinocheirus.

(Copyright: Public Domain: Wikipedia)

(Copyright: Public Domain Wikipedia)

            Deinocheirus is known by only one species, coined Mirificus, which translates to ‘wonderful’. It is now known that Deinocheirus was a giant amongst Ornithomimids. It towered at a height of 3.5 to 6 meters and measured a length of 11 meters, and could have weighed as much as 6 tons; Deinocheirus is the largest example of Ornithomimosauria that currently exists. The fossils of Deinocheirus suggest omnivory, due to evidence of piscivory and herbivory found in its stomach. Gastroliths (stones swallowed to aid in digestion) and fish scales were found in the stomach cavity of the skeleton and points to a varied diet of plants, fish, and probably other types of vegetation like fruit. Deinocheirus lived during the Late Campanian/Early Maastrichtian of the Cretaceous Period of what is now Mongolia.

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       Deinocheirus’ relatives are Garudimimus and Beishanlong. All three of these animals make up their own family within Ornithomimosauria and share the characteristics of a slower mode of life and a bulkier build than most other Ornithomimids. Deinocheirus, being an omnivore, would have had little competition from its contemporaries with the only exception being Therizinosaurus; both shared similar characteristics and were likely omnivorous. 

      Deinocheirus shared its ecosystem with a wide range of animals like Tarbosaurus, Pinacosaurus, Saichania, Protoceratops, Oviraptor, Velociraptor, and more. Evidence strongly suggests that the first specimen met its end from a Tarbosaurus (a Mongolian relative of Tyrannosaurus) and, as such, must have been a predator of Deinocheirus. Alioramus, another relative to Tyrannosaurus, may have preyed on Deinocheirus as well. Deinocheirus lived in a place that, at the time, was home to vast swamps and river ways, which would have provided it a niche that most other herbivores and even most carnivores had yet to adapt to; Omnivory.

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     The Paleontologists that found Deinocheirus quickly determined it to be a Theropod; however, what kind was impossible to know. At the time, 1965, the scientists thought the arms belonged to a massive carnivorous carnosaur-like animal. At this point in history, most carnivorous theropods were thrown together into one phylogenetic ‘unnatural’ grouping called Carnosauria (This has since been revoked due to further variation amongst the Theropoda family tree). Deinocheirus became identified as something other than a carnivorous Theropod only after the gastralia material had been found. The discovery of Therizinosaurid dinosaurs, like Nothronychus and Segnosaurus, made the possibility of herbivorous theropods a reality. Paleontologists had been debating whether Deinocheirus was an Ornithomimid or a Therizinosaurid until the latest skeletal discovery made the decision. Even though science knows more about Deinocheirus than ever before, aspects of its paleobiology and habits are still unknown and only more material will unearth the secret of Mongolia.

(Copyright: Art belongs to Geocities)

(Copyright: Scale belongs to PrehistoricWildlife)

Works Cited

"Deinocheirus." Wikipedia. Wikimedia Foundation, n.d. Web. 03 Nov. 2015.

Yong, Ed. "Deinocheirus Exposed: Meet The Body Behind the Terrible Hand." Phenomena Deinocheirus Exposed Meet The Body Behind the Terrible Hand Comments. National Geographic, 22 Oct. 2014. Web. 03 Nov. 2015.

"Deinocheirus." Deinocheirus. PrehistoricWildlife, n.d. Web. 03 Nov. 2015.

Perkins, Sid. "Fossils Reveal 'beer-bellied' Dinosaur." Nature.com. Nature Publishing Group, 22 Oct. 2014. Web. 03 Nov. 2015.

Paleo Files: Albertosaurus

• Pronunciation: (Al-Burt-Oh-Sore-Us)
• Name Meaning: "Alberta Lizard"
• Height: 9ft
• Weight: up to 2.5 tons
• Length: 26-29ft
• Diet: Carnivorous
• Time: Cretaceous (70 MYA)
• Region: North America (Canada)

Albertosaurus Bust (Art and Copyright belongs to Heraldo; BrokenMachine86 on DeviantArt)

Albertosaurus, the top predator of late cretaceous Canada, is one of the most well known theropods among the vast majority of fragmentary ones. Albertosaurus got its name from the province of Canada in which it was discovered. The top predator of its region, the “Alberta Lizard” would have had no other predators big enough to complete for resources with in the northern parts of North America. Albertosaurus shows a wonderful example in the line of Tyrannosaur evolution showing a transition from a lithe and streamlined form into that of a more heavily built predator like Daspletosaurus and eventually Tyrannosaurus.

Albertosaurus with Feathery Coat (Note: Albertosaurus lived so far north, even in the cretaceous, that it may have seen snow)
(Art and Copyright belongs to StygimolochSpinifer on DeviantArt)

The type specimen of Albertosaurus consists of a partial skull. This specimen came from the Horseshoe Canyon Formation near the Red Deer River in Alberta, Canada. Paleontologist, Joseph Burr Tyrell, uncovered the type specimen; however, he could only partially secure the find, due to lack of specialized equipment, and only acquired a part of the skull. In 1889 Tyrell’s colleague, Thomas Chesmer Weston, found another specimen, this time being an incomplete skull smaller than the first and located nearby. These two specimens were placed under the species, Laelaps incrassatus, named by Edward Drinker Cope in 1892. The name Laelaps had been previously attributed to a kind of mite and thus made the name a nomen dubium. Othniel Charles Marsh, Cope’s rival, renamed the genus Dryptosaurus in 1877. Edward Drinker Cope refused to acknowledge his rival’s decision and continued to use Laelaps as a legitimate name. Many remains were uncovered after the fact, going unnamed until Henry Fairfield Osborn, a well-known American Paleontologist, coined the name Albertosaurus in 1905 when he wrote his description of the much larger, Tyrannosaurus. Later on, in the year 1910, famed paleontologist, Barnum Brown, uncovered the remains of a mass of Albertosaurus near the Red Deer River. Due to the large amount of individuals, Brown and his expedition were unable to collect all of the specimens. They took the important identifying fossils, which told them that at the site lay at least nine individuals. All in all, 1,128 Albertosaurus fossils had been uncovered from the bone-bed; the largest concentration of Theropod fossils ever found in Cretaceous sediments, which is why so much is known about this animal’s biology.

Albertosaurus Skeleton

Due to the large amounts of sizes and ages of the individuals discovered near the Red Deer River, the ontogenetic cycles of growth for Albertosaurus is relatively well known. Remains Approximately two years of age, measuring six feet long and weighing no less than one hundred and ten pounds showcased the youngest individual. The eldest specimen found consisted of a length of thirty-three feet and might have been twenty-eight years of age at the time of death. The growth and death rates of the bone-yard in the Red Deer River compared with the other Albertosaurus finds suggest that the animal grew at an exceedingly fast rate along a four-year period that ended at approximately age sixteen which began the onset of sexual maturity. This growth is unlike most Avians and is more akin to the growth rates of large mammals. These statistics also revealed a hypothesis concerning the mortality rate. The theory suggests that the hatchlings had a rather high mortality rate, explaining why fossils of young individuals have not been commonly discovered. Then, after two years of growth, the animals would have been much larger than many of the predators it shared its ecosystem with and the death mortality decreased sharply. However, the mortality rate again increased, doubling at around the age of twelve and then doubling again around the age of sexual maturity. The find of dozens of specimens in the bone-bed of the Red Deer River might suggest that the animals hunted together in packs. This theory has been suggested for many theropods found together. But the opposing theory to this is that they may have been killed due to environmental reasons and then deposited together after death. Canadian Paleontologist, Philip J. Currie, suggests that the legs of the younger Albertosaurus might have helped them draw the prey towards the adults that were slower and more powerful. Currie speculates that the young Albertosaurus, having different adaptations compared with the adults, may have had a different way of life similar to the Komodo Dragon of the present (young live the lives of insectivores, while adults are the largest predators on their island, attacking and killing water buffalo). Due to the fact that behavior does not fossilize, Currie’s theory is speculation and cannot be tested. However, what can be observed is what it lived with and what it may have hunted.

Contemporaries of Albertosaurus (Art and Copyright belongs to Geocities)

All of the Albertosaurus material is known from Canada, most of which is from the Horseshoe Canyon Formation housing fossils from the Maastrichtian age of the Cretaceous period. Other species found in and around this area and time include; Didelphodon, Champsosaurus, Saurolophus, Hypacrosaurus, Albertonykus, Pachyrhinosaurus, Ornithomimus, Stegoceras, and many more. Albertosaurus would have been the top predator of this ecosystem and might have preyed on most of these animals. However, Pachyrhinosaurus grew to be one of the largest Ceratopsians dinosaurs in existence and would have given even an adult Albertosaurus trouble (potentially evidence for pack behavior). Albertosaurus may have lived with its cousins Gorgosaurus and Daspletosaurus. Albertosaurus is placed inside the subfamily, Albertosaurinae, the only other member being Gorgosaurus. This subfamily showcases animals of a slim build and capable of quick movements unlike their descendants which include; Daspletosaurus, Teratophoneus, Bistahieversor, Tyrannosaurus, and Tarbosaurus.

This predator may have been at the top of the food chain, but environmental disasters have no bias and kill without mercy. Whether Albertosaurus fell prey to the elements, or each other, they all ended up in the same place. To be uncovered by our species many of millions of years later. We learn from these fossils of how the earth was at a previous time to help us understand the earth as it is today.

Art and Copyright belongs to Prehistoric Wildlife

Works Cited:

"Albertosaurus." Wikipedia. Wikimedia Foundation, n.d. Web. 24 Dec. 2015. <https://en.wikipedia.org/wiki/Albertosaurus>.

"Albertosaurus- Enchanted Learning Software." Albertosaurus- Enchanted Learning Software. Enchanted Learning, n.d. Web. 24 Dec. 2015. <http://www.enchantedlearning.com/subjects/dinosaurs/dinos/Albertosaurus.shtml>.

"Albertosaurus." Dinopedia. Wikipedia, n.d. Web. 24 Dec. 2015. <http://dinopedia.wikia.com/wiki/Albertosaurus>.

"Albertosaurus." HowStuffWorks. HowStuffWorks, 19 Mar. 2008. Web. 24 Dec. 2015. <http://animals.howstuffworks.com/dinosaurs/albertosaurus.htm>.

"Albertosaurus Libratus - a Tyrannosaur Dinosaur from the Late Cretaceous." Albertosaurus Libratus - a Tyrannosaur Dinosaur from the Late Cretaceous. Feenixx, n.d. Web. 24 Dec. 2015. <http://www.dinosaur-world.com/tyrannosaurs/albertosaurus_sarcophagus-include.htm>.

"Albertosaurus." Albertosaurus. Prehistoric Wildlife, n.d. Web. 24 Dec. 2015. <http://www.prehistoric-wildlife.com/species/a/albertosaurus.html>.

"Albertosaurus Cretaceous Dinosaur." Albertosaurus Dinosaur. Fossil Museum, n.d. Web. 24 Dec. 2015. <http://www.fossilmuseum.net/DinosaurFossils/Albertosaurus/albertosaurus.htm>.

"The Dino Directory - Albertosaurus - Natural History Museum." The Dino Directory - Albertosaurus - Natural History Museum. Natural History Museum, n.d. Web. 24 Dec. 2015. <http://www.nhm.ac.uk/discover/dino-directory/albertosaurus.html>.

"Australian Museum." Albertosaurus Sarcophagus -. Australian Museum, n.d. Web. 24 Dec. 2015. <http://australianmuseum.net.au/albertosaurus-sarcophagus>.