(China, 90 million BCE -- "before the common era"; same dating as "BC")
Normally paleontologists name new dinosaurs and other extinct animals based on bones. But when the relevant animal's skeleton is nowhere to be found, paleontologists also assign scientific names to trace fossils such as footprints, burrows, and eggs. In 1995, scientists coined the genus (the first name; think Homo in Homo sapiens) Macroelongatoolithus for colossal, elongated dinosaur eggs from China's Henan Province. Similar fossils have since been found in Mongolia, South Korea, and the western United States, measuring between 13 and 24 inches long and laid by similar dinosaur species dating from the Early to Late Cretaceous Period (about 125 to 66 million BCE).
One of the original Macroelongatoolithus specimens from Henan contained a dinosaur embryo nicknamed "Baby Louie". In 2017, an international team of paleontologists identified "Baby Louie" as a new dinosaur genus, which they dubbed Beibeilong ("baby dragon"). This creature belonged to the oviraptorosaurs, a family of beaked, feathered theropods. Unlike most other theropods, these dinosaurs seem to have been herbivores that plucked branches and cracked open fruits with their strange beaks. The size of the eggs suggest that Beibeilong was among the largest oviraptorosaurs. Had he or she hatched and reached maturity, "Baby Louie" may have measured up to 26 feet long and weighed between 2 and 3 tons.
Borealopelta and Zuul
(Alberta, 110 million BCE and Montana, 75 million BCE, respectively)
Compared to most other dinosaur groups, the ankylosaurs have a rather crude fossil record. Most of these armored dinosaurs are known only from isolated skulls, tail clubs, and plates, leaving size estimates and the exact arrangement of their armor open to debate. In 2017, however, two remarkably complete and distinct ankylosaurs were introduced to the general public:
Zuul is now the most complete ankylosaur known from the Late Cretaceous of North America. This dinosaur was discovered in Montana in 2016 and is known from a single specimen that includes the complete skull and tail club, armored plates, and even impressions left by its scaly skin. Zuul is set apart from its closest relatives by its age and location, the shape of its skull, the arrangement of horns on its muzzle, and a row of thorny plates along each side of the tail.
In life, Zuul measured 20 feet long and weighed about 2.75 tons. It would have cropped low-lying vegetation with its beak and ground it up with its fluted, peg-like teeth. While ankylosaur plates and clubs have generally been interpreted as defenses against predators like tyrannosaurs, they may also have been in battles with each other for food, territory, or mating rights.
Zuul is named for the horned, dog-like monster from the first Ghostbusters film. On a more trivial note, this dinosaur is now alphabetically the last dinosaur genus identified thus far, succeeding Zupaysaurus.
Borealopelta ("northern shield") might not roll off the tongue as easily as Zuul, but is no less astounding. This ankylosaur died over 110 million years ago and was quickly buried at the bottom of the Western Interior Seaway, a shallow sea that bisected North America for most of the Cretaceous Period. Local miner Shawn Funk stumbled upon the skeleton in March of 2011, spotting its fossilized ribs poking through the rock layer. Over the course of two weeks, a joint team of local paleontologists, miners, and university students extracted a 7.5-ton slab of rock from the site, and over the next six years, Mark Mitchell of the Royal Tyrell Museum in Drumheller freed the dinosaur from the slab.
While dinosaur "mummies" preserving the animals' skin, flesh, and bone have been known for over a century, the original specimen of Borealopelta is the most complete by far: It not only includes skin impressions and half of the skeleton, but the dinosaur's armored plates, which remain fixed in their original positions and covered in keratin sheaths. This dinosaur was also preserved in three dimensions instead of crushed under layers of sediment, giving paleontologists a better idea of its weight and musculature. Jakob Winther, one of the scientists involved in the study of Borealopelta even believe the scales contain traces of red pigment and indicate that the dinosaur had counter-shading colors for camouflage (though not all experts are convinced by this claim).
Unlike Zuul, this herbivore belonged to the nodosaurids, a family of ankylosaurs with narrow muzzles, unclubbed tails, and huge spikes jutting from the neck and shoulders.
From the YouTube channel BestInShot
(Argentina, 100 million BCE)
Titanosaurs were the largest, last, and most successful of the long-necked, long-tailed sauropods. Their fossils have been found on every continent but Antarctica (though it's probably only a matter of time) and in life, these dinosaurs ranged from the size of horses to longer than the biggest blue whales.
In 2014, the world was introduced to the 85-foot-long, 65-ton Dreadnoughtus, the latest in a succession of super-sized titanosaurs to be discovered in Argentina and the most complete of these dinosaurs to date, with 70 percent of its skeleton known to science. That same year, scientists announced a less complete but even larger titanosaur from the same country. After determining that it was distinct enough from other super-sized Argentine titanosaurs, the dinosaur's discoverers gave it a name in August of 2017 -- Patagotitan ("Patagonian giant").
Initial size estimates for Patagotitan projected a length of 130 feet and a weight of 85 tons. More recent calculations have brought these figures down to 122 feet long and 69 tons, but still make this creature is the leading candidate for the biggest dinosaur (and land animal) of all time.
That said, the known remains of Patagotitan are still far from representing a complete skeleton: The entirety of its skull and feet are still missing, as are most of its neck and tail. Like Dreadnoughtus and other super-sized titanosaurs, the projected size and anatomy of Patagotitan are based on more than one specimen, and the scaled-up remains of similar dinosaurs were used to inform visual representations of this animal. These factors make determining which dinosaur was the largest -- and how just large it was -- an incredible challenge for paleontologists. It's also quite possible in the next few years, sauropod experts will dispute or diminish the current measurements for Patagotitan.
For the time being, however, this new giant has strongest claim for the title of biggest dinosaur, outstripping previous front-runners like Argentinosaurus and Puertasaurus for both completeness and sheer size.
Afromimus- Ornithomimosaur from Early Cretaceous Niger. One of the oldest members of its family and the second known from Africa; the other, Nqwebasaurus, is the oldest-known ornithomimosaur, suggesting that these dinosaurs may have originated on this continent.
Burianosaurus- Small ornithopod from the mid-Cretaceous of the Czech Republic. Named in honor of Czech paleoartist Zdeňek Burian (1905-1981).
Chenanisaurus- Abelisaur from latest Cretaceous Morocco and currently the latest-known non-avian dinosaur from Africa.
Corythoraptor- Long-necked oviraptorosaur from Late Cretaceous China with a large, cassowary-like head crest.
Halszkaraptor- Long-necked dromaeosaur from Late Cretaceous Mongolia with a goose-like snout. Its describers believe it was semi-aquatic but not all paleontologists are convinced. Named after Polish paleontologist Halszka Osmolska (1930-2008).
Isaberrysaura- Strange ornithischian ("bird-hipped") dinosaur from the mid-Jurassic of Argentina with cycad seeds preserved in its gut. Initially interpreted as a primitive ornithopod but may actually be an early stegosaur.
Latenivenatrix- Troodontid from Late Cretaceous Alberta and the largest troodontid to date, measuring between 10 and 11.5 feet long in life.
Matheronodon- Rhabdodont ornithopod from Late Cretaceous France with scissor-like jaws and teeth.
Mierasaurus- Sauropod from Early Cretaceous Utah and the first of the mysterious turiasaurs to be found outside of Europe.
Vouivria- Early brachiosaur from mid-Jurassic France.
Yehuecauhceratops- High-nosed, short-horned ceratopsian from Late Cretaceous Mexico. It is most closely related to Avaceratops and Nasutoceratops and is one of the smallest ceratopsids (large horned dinosaurs) known to date, measuring a mere 10 feet long.
Bonapartesaurus- Hadrosaur from Late Cretaceous Argentina. Formerly classified as “Willinakaqe” (“duck mimic”) but the describers of Bonapartesaurus argue that the fossils used to describe Willinakaqe represented more than one dinosaur species.
Ostromia- Bird-like theropod from Late Jurassic Germany. It was first interpreted as a pterosaur in 1857, then as a specimen of Archaeopteryx in 1970, and finally as dinosaur similar to Anchiornis in 2017.
Stenonychosaurus- Troodontid from Late Cretaceous Alberta that lived alongside the much larger Latenivenatrix. Stenonychosaurus was initially described in 1932 and relegated as a synonym of Troodon in 1987 by paleontologist Phil Currie. This year, however, Currie and his student Aaron van der Reest resurrected the genus, arguing that like Willinakaqe, fossils assigned to Troodon represented multiple species.
“Troodon…has been found from Mexico all the way to Alaska, spanning a 15 million year period,” said van der Reest. “A fantastic and unlikely feat.”
Cruzado-Caballero, Penélope and Jaime Powell. “Bonapartesaurus rionegrensis, a new hadrosaurine dinosaur from South America: implications for phylogenetic and biogeographic relations with North America.” Journal of Vertebrate Paleontology, Vol. 37, Issue 2, 20 April 2017.
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Greshko, Michael. "It's Official: Stunning Fossil Is a New Dinosaur Species." National Geographic News, 3 Aug 2017.
Greshko, Michael. "The Amazing Dinosaur Found (Accidentally) by Miners in Canada." National Geographic, June 2017.
Guglielmi, Giorgia. "Did this big dinosaur camouflage to hide from predators?" Science, 3 Aug 2017.
Henderson, Donald. "A one-in-a-billion dinosaur find." The Guardian, 13 May 2013.
de Lazaro, Enrico. "Meet Patagotitan mayorum, Biggest Animal Ever to Walk Earth." Sci-News.com, 11 Aug 2017.
Morgan, James. "'Biggest dinosaur ever' discovered." BBC News, 17 May 2014.
www.rom.on.ca/en/collections-research/research-community-projects/zuul (profile on Zuul at the Royal Ontario Museum's website)
Salgado, Leonardo et al. "A new primitive Neornithischian dinosaur from the Jurassic of Patagonia with gut contents." Scientific Reports, Vol, 4, Article No. 42,778, 16 Feb 2017.
Simon, D. J. "Giant Dinosaur (theropod) Eggs of the Oogenus Macroelongatoolithus (Elongatoolithidae) from Southeastern Idaho: Taxonomic, Paleobiogeographic, and Reproductive Implications." Montana State University, Bozeman, MT, May 2014. (Doctoral dissertation)
Switek, Brian. “Baby Louie Gets a New Name.” Scientific American, 11 May 2017.
Switek, Brian. "Introducing 'Zuul,' an Ankylosaur That Could Really Make Your Ankles Sore." Smithsonian.com, 8 May 2017.
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Switek, Brian. “Paleo Profile: The Hidden Hunter.” Scientific American, 18 Aug 2017.
Switek, Brian. “Paleo Profile: The Wyvern Dinosaur.” Scientific American, 12 May 2017.
“Two New Cretaceous Dinosaur Species Discovered in Canada.” Sci-News.com, 9 Aug 2017.