First American Dinosaurs 1856
The first scientifically studied dinosaurs were discovered in England during the early part of the 19th century. By 1842 (the year Richard Owen first proposed the name Dinosauria) several species of these Mesozoic giants were known from fragmentary fossils (1).
About a decade later (1855), Ferdinand V. Hayden collected some fossils at the confluence of the Judith and Missouri Rivers in Montana while on a geological survey. The fossils, which included an assortment of species, were forwarded to Joseph Leidy in Philadelpha.
Upon review of the fossils, Leidy noted that the Judith River fossils were similar to Cretaceous fossils he had examined while on a trip to Europe in 1850. In particular, there were two groups of teeth that were similar to those of two English dinosaurs, the meat-eating Megalosaurus and plant-eating Iguanodon. He identified them as the teeth of dinosaurs and named those of the meat-eater Deinodon horridus, and those of the plant-eater Trachodon mirabilis (2). Leidy had identified the first dinosaurs of North America.
Leidy also noted that the other fossils, which included two fishes, a crocodile and two small teeth with lizard-like characteristics belonged to two new species. He named these lizard-like teeth Palaeoscincus costatus and Troodon formosus (3). Leidy reported his findings in a short publication in 1856. He published a longer, more detailed article with lithographic illustrations in 1860 (4).
Selected fossil teeth of the first American dinosaurs. These fossils are details from a lithograph published by Leidy in 1860. Click here or on the fossils to view the full lithograph.
Later paleontologists have determined that all four kinds of teeth represent true dinosaurs. The names of three of them, however, are considered invalid because isolated teeth are usually not sufficient for defining dinosaur genera and species. We know that Deinodon was a moderately large therapod (two-legged, meat-eating dinosaurs) and several authors attribute it to Albertosaurus. Palaeoscincus was a nodosaurid ankylosaur (armored dinosaur). Trachodon was a hadrosaur (duck-billed dinosaurs).
The only one of these four dinosaurs to retain its name is Troodon formosus. Ironically, Leidy hadn't identified the tooth as belonging to a dinosaur. In fact, the status of Troodon wasn't reasonably resolved until the 1980s. Several other dinosaurs (Pectinodon, Polydontosaurus, Saurornithoides, Stenonycosaurus) known only from fragmentary material are now considered to be Troodon.
Websites:
- George Olshevsky's web page
on the status of Trachodon.
www.dinosauria.com/jdp/misc/trachodon.html
Notes:
- The
most famous of these early european dinosaurs were Megalosaurus (first
published on by William Buckland in 1824) and Iguanodon (described
and named by Gideon Mantell in 1826).
[go back] - Etymology for Deinodon and Trachodon:
Deinodon (DIE-no-don) = terrible tooth
horridus (HOR-rid-us) = horrible
Trachodon (TRACK-oh-don) - rough tooth
mirabilis (me-RA-bi-lis) = wonderful
[go back] - Etymology for Palaeoscincus and Troodon:
Palaeoscincus (PAY-lee-oh-SKINK-us) = ancient skink
costatus (cos-TAY-tus) = ribbed
Troodon (TRUE-oh-don) = wounding tooth
formosus (for-MOE-sus) = beautiful, well-formed
[go back] -
The short notice in 1856
is: "Notice of remains of extinct reptiles and fishes, discovered by Dr. F. V.
Hayden, in the Bad Lands of of the Judith River, Nebraska Territory". Proceedings
of The Academy of Natural Sciences of Philadelphia 8(1): 59.
The longer 1860 article is: "Extinct Vertebrates from the Judith River and Great Lignite Formation of Nebraska". Transactions of the American Philosophical Society 8-11 (1860): 139-154.
[go back]