| Loncosaurus
Temporal range: Late Cretaceous, 76–66 Ma
| |
|---|---|
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | †Ornithischia |
| Clade: | †Neornithischia |
| Clade: | †Ornithopoda |
| Genus: | †Loncosaurus Ameghino, 1899 |
| Species: |
†L. argentinus
|
| Binomial name | |
| †Loncosaurus argentinus Ameghino, 1899 | |
| Synonyms | |
| |
Loncosaurus (meaning uncertain; either Araucanian "chief" or Greek "lance" "lizard"[1]) is an extinct genusofornithopod dinosaur from the Upper CretaceousofProvincia de Santa Cruz, Argentina. The type (and only known) speciesisLoncosaurus argentinus, described by the famous Argentinian paleontologist Florentino Ameghino, but is considered a dubious name. Details on this animal are often contradictory, befitting a genus that was long confused for a theropod.
Teeth attributed to cf. "Carnosaurus" may have actually belonged to Loncosaurus.[2]
The holotype femur and tooth were discovered by Carlos Ameghino, Florentino's brother, between 1887 and 1898.
Ameghino named this dinosaur in 1899[3][4][5][6][7][8][9][10][11] from a proximal femur (MACN-1629) and tooth found near Rio Sehuen, Santa Cruz, in the Cardiel Formation[10] (Upper Cretaceous).
Either way, he thought the remains belonged to a "megalosaurid" dinosaur, a carnivore, which Friedrich von Huene agreed with.[12] Upon further review, von Zittel assigned it to the Coeluridae,[13] recognized today as a "wastebasket taxon" for small carnivorous dinosaurs. The carnivore tooth helped this misidentification take hold.
It was ignored for decades until Ralph Molnar reassessed it.[14] He found that the tooth did not belong to the same animal as the femur and removed it from the type, and suggested that the femur belonged to a hypsilophodontorturtle. Professional opinion has not changed much since then, although based on size, it appears more likely to be an iguanodont than a hypsilophodont.[10] Reviews either put it at Ornithopoda incertae sedis[10] or Iguanodontia.[4][5] Oddly, a semipopular reference reassigned it to Genyodectes without comment,[15] a view which has not been followed since.
Coria estimates the size of the Loncosaurus type individual at about 5 m (16.4 feet) long.[10] As a small to medium-sized ornithopod, it would have been an agile bipedal herbivore.[5]
| Loncosaurus argentinus |
|
|---|---|
