Dinosaur Discoveries of 2015
Unfortunately, I didn't have time last December to discuss the new dinosaurs of 2015. Before reviewing the new dinosaurs of 2016, here are the most noteworthy dinosaurs that debuted (or in one case, returned) last year:
(Utah and Wyoming, 155-150 million BCE)
In a huge, five-year study eventually published in April last year, paleontologists Octávio Mateus, Emanuel Tschopp, and Roger Benson re-assessed the evolutionary relationships of Apatosaurus, Diplodocus, and the other long-necked, whip-tailed sauropods (known collectively as the diplodocoids). One of their conclusions was that three of these animals -- two species of Apatosaurus and a dinosaur initially named "Eobrontosaurus" -- were anatomically distinct from other diplodocoids, but close enough to each other to fall under the same genus (think Homo in Homo sapiens). Instead of giving these three species a new scientific first name, they restored Apatosaurus excelsus' old one: Brontosaurus ("thunder lizard").
This dinosaur was first described in 1879 by Othniel C. Marsh. At the time, it was the largest and most-complete known sauropod, and eventually became the first of its kind to have its skeleton mounted in a museum (often with the wrong head; see lower opposite graphic). Along with Stegosaurus, Triceratops, and T. rex, it became a movie star, appearing in The Lost World (1925), King Kong (1933), and Fantasia (1940).
As early as 1903, however, some scientists questioned whether it was all that different from other sauropods. Because Apatosaurus had been named earlier and there weren't enough anatomical features to distinguish Brontosaurus from it, paleontologist Elmer Riggs of Chicago's Field Museum determined that the later name had to go. By the end of the twentieth century, the majority of paleontologists agreed with Riggs' conclusion. According to Mateus, Tschopp, and Benson, however, all three species of Brontosaurus were considerably lighter than Apatosaurus and each had a much narrower neck.
Most prominent paleontologists interviewed were happy about Brontosaurus' return and impressed by the trio's paper. Not everyone, however, was convinced: Dr. Donald Prothero, an expert on the largest land mammals, questioned whether an ecosystem could feed so many gigantic sauropod species at once, pointing to the eight the paper recognized from Utah's Dinosaur National Monument alone. For comparison, he pointed to the modern African savanna, which sustains only one species of elephant, and the Ice Age "mammoth steppe", which extended from Spain to Alaska and supported only one kind of mammoth at a time.
(Chile, 150 million BCE)
One of the few Jurassic dinosaurs known from South America, the ten-foot-long Chilesaurus has no close known relatives. It was clearly a theropod -- a member of the same huge order as T. rex, Velociraptor, and countless other meat-eating dinosaurs -- but doesn't fit neatly into any known theropod family. Unlike most of these dinosaurs, Chilesaurus had a short muzzle lined with blunt, spoon-shaped teeth, indicating that it was a herbivore. In addition, only two of this animal's three fingers ended with sharp claws.
As of writing, paleontologists regard the dinosaur as a basal member of the Tetanurae ("hollow tails"), a sub-group that contains the majority of known theropods. Unless proven to be a member of a previously-described family, Chilesaurus marks the fifth known instance of theropods independently evolving from carnivores to herbivores -- at least four times within the Tetanurae and once outside of it.
(Alberta, 68 million BCE)
Almost all known large ceratopsians lived in North America during the last fifteen million years of the Cretaceous, and most of them belong either to the centrosaurines or the chasmosaurines. Until recently, paleontologists used these dinosaurs' horn arrangements to define these subfamilies: Long nasal horns, less developed brow horns, and elaborately-horned frills were regarded as exclusive to centrosaurines, while short nasal horns, long brow horns, and less spiky frills were seen as trademarks of chasmosaurines.
This rule of thumb began to erode after the description of centrosaurines with long brow horns such as Albertaceratops (in 2007) and Nasutoceratops (2013), and with the debut of Regaliceratops, it's now obsolete. This new chasmosaurine's skull had the same arrangement and number of horns as Triceratops, but they were proportioned like those of a centrosaurine: The nasal horn was long, the brow horns were short, and those lining the frill were large and spade-like.
Regaliceratops also lived at a critical juncture in the history of large ceratopsians: Most fossil sites with these dinosaurs have at least one local centrosaurine and one local chasmosaurine if they date from 80 to 70 million years old. To date, no centrosaurines are known from later than 69 million years ago, and most sites dating from 68 to 66 million years ago have only Triceratops and/or Torosaurus. Regaliceratops, then, may have been the last local, unique ceratopsian before being replaced by these two larger relatives.
(China, 160 million BCE)
Feathered dinosaurs from China are nothing new by now. Yet almost everyone was surprised by Yi, a tiny theropod that not only had short, downy feathers and long tail plumes, but also long fingers that formed leathery, bat-like wings.
It belonged to the scansoriopterygids ("climbing wings"), a recently-discovered family of tiny, tree-dwelling theropods known only from the Middle to Late Jurassic (160-145 million BCE) of China. The three known members of this family (Scansoriopteryx, Epidexipteryx, and Yi) all had huge hands with disproportionately long outer fingers. Two of them (Epidexipteryx and Yi) had short tails ending in four, ribbon-like display feathers. Only Yi, however, would have been capable of flying or gliding. More importantly, however, this creature is a reminder that some small, meat-eating dinosaurs developed their own means of aerial locomotion without evolving into birds.
One final note about this dinosaur: Its full scientific name, Yi qi ("strange wing"), is now the shortest of any dinosaur described to date, and is tied with the great evening bat's -- Ia io -- for the shortest of any animal species.
What was the most important dinosaur described in 2015?
Dakotaraptor- 18-foot long dromaeosaur from latest Cretaceous South Dakota. Lived alongside T. rex and Triceratops, and like them was one of the largest and last dinosaurs of its kind.
Morrosaurus- Small ornithopod from Late Cretaceous Antarctica and the fourth dinosaur described from this continent.
Padillasaurus- Brachiosaur from Early Cretaceous Colombia. The first dinosaur known from this country, as well as the first brachiosaur known from South America.
Tototlmimus- Ornithomimosaur from Late Cretaceous Mexico. One of succession of new dinosaurs being discovered in this country, many of which have close relatives from the United States and Canada.
Wendiceratops- Large ceratopsian from Late Cretaceous Alberta. It is ten million years older than Regaliceratops, and unlike this dinosaur, it was a centrosaurine with long brow horns and a shorter nasal horn. Named after local fossil hunter Wendy Sloboda.
OTHER RENAMED DINOSAURS
Crichtonpelta- A medium-sized ankylosaur from mid-Cretaceous China. Fossils belonging to this animal were previous assigned to another ankylosaur called Crichtonsaurus. Both dinosaurs are named after Michael Crichton, author of Jurassic Park.
Galeamopus- A large sauropod from Late Jurassic Wyoming, formerly known as "Diplodocus hayi". Rechristened in the same study that resurrected Brontosaurus.
Horshamosaurus- An earlier medium-sized ankylosaur than Crictonpelta from Early Cretaceous England. Formerly called "Polacanthus rudgwickensis".
Kunbarrasaurus- Small, unusually complete ankylosaur from Early Cretaceous Australia, formerly assigned to Minmi.
Ugrunaaluk- Hadrosaur from Late Cretaceous Alaska, originally regarded as a form of Edmontosaurus. Though global temperatures were higher 70 million years ago, Alaska was further north at that time, and this dinosaur (whose name is Inupiat for "ancient grazer") almost certainly saw and lived through snow. Also the northern-most dinosaur described to date.
Anderson, Natali. "Kunbarrasaurus ieversi: New Armored Dinosaur Species Discovered." Sci-News.com, 11 Dec 2015.
Brown, Caleb M. and Donald M. Henderson. "A New Horned Dinosaur Reveals Convergent Evolution in Cranial Ornamentation in Ceratopsidae." Current Biology, Vol. 25, Issue 12, p. 1641–1648, 15 June 2015.
"Chilesaurus diegosuarezi: New Herbivorous Dinosaur Discovered in Chile." Sci-News.com, 28 Apr 2015.
Choi, Charles. "The Brontosaurus Is Back." Scientific American, 7 Apr 2015.
Depra, Dianne. "Who Said Brontosaurus Is Not Real? It's Back. It's Real." Tech Times, 7 Apr 2015.
"Este es el Padillasaurus, el primer dinosaurio colombiano." El Tiempo, 17 Sept 2015.
Fastovsky, David E. and David B. Weishampel. Dinosaurs: A Concise Natural History (1st Edition). Cambridge University Press, New York, NY, 2009.
Martins, Ralph. "Brontosaurus Stomps Back to Claim Its Status as Real Dinosaur." National Geographic, 7 Apr 2015.
McDonald, Andrew. "New plant-eating dinosaur discovered in Antarctica." Science Recorder, 1 Oct 2015.
Nogrady, Bianca. "Meet Kunbarrasaurus: Australia's newest dinosaur." ABC News, 8 Dec 2015.
"Northernmost Dinosaur Discovered in ‘Lost World’ of Animal Fossils in Alaska." Western Digs, 25 Sep 2015.
Prostak, Sergio. "Dakotaraptor steini: Giant, Feathered Dromaeosaurid Dinosaur Discovered in South Dakota." Sci-News.com, 5 Nov 2015.
Prothero, Donald. "Is 'Brontosaurus' Back? Not So Fast!" Skeptic, 30 Apr 2015.
"Regaliceratops peterhewsi: New Horned Dinosaur Discovered in Canada." Sci-News.com, 5 Jun 2015.
Sample, Ian. "'Bizarre' Jurassic dinosaur discovered in remarkable new find." The Guardian, 27 Apr 2015.
Switek, Brian. "Back to Brontosaurus? The Dinosaur Might Deserve Its Own Genus After All." Smithsonian Magazine, 7 Apr 2015.
Switek, Brian. "Paleo Profile: Mexico's 'Bird Mimic'." National Geographic, 30 Oct 2015.
Tamplin, Harley. "Dinosaur renamed Horshamosaurus after town." West Sussex Today, 18 Sept 2015.
"Ugrunaaluk kuukpikensis: New Duck-Billed Dinosaur Species Discovered in Alaska." Sci-News.com, 22 Sep 2015.
"Wendiceratops: New Genus and Species of Horned Dinosaur Discovered in Canada." Sci-News.com, 9 Jul 2015.
"Yi qi: Bat-Winged Dinosaur Discovered in China." Sci-News.com, 30 Apr 2015.
Yong, Ed. "Chinese Dinosaur Had Bat-Like Wings and Feathers." National Geographic, 29 Apr 2015.