| Loncosaurus | |
|---|---|
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | †Ornithischia |
| Clade: | †Ornithopoda |
| Genus: | †Loncosaurus Ameghino, 1899 |
| Species: | †L. argentinus |
| Binomial name | |
| †Loncosaurus argentinus Ameghino, 1899 | |
| Synonyms | |
| |
Loncosaurus (meaning uncertain; eitherAraucanian "chief" orGreek "lance" "lizard"[1]) is an extinctgenus ofornithopoddinosaur from theUpper Cretaceous ofProvincia de Santa Cruz,Argentina. Thetype (and only known)species isLoncosaurus argentinus, described by the famousArgentinianpaleontologistFlorentino Ameghino, but is considered adubious name. Details on this animal are often contradictory, befitting a genus that was long confused for atheropod.
Teeth attributed tocf. "Carnosaurus" may have actually belonged toLoncosaurus.[2]
The holotypefemur andtooth were discovered byCarlos Ameghino, Florentino's brother, between 1887 and 1898.
Ameghino named this dinosaur in 1899[3][4][5][6][7][8][9][10][11] from aproximal femur (MACN-1629) and tooth found nearRio Sehuen, Santa Cruz, in theCardiel Formation[10] (Upper Cretaceous).
Either way, he thought the remains belonged to a "megalosaurid" dinosaur, acarnivore, whichFriedrich von Huene agreed with.[12] Upon further review, von Zittel assigned it to theCoeluridae,[13] recognized today as a "wastebasket taxon" for smallcarnivorous dinosaurs. The carnivore tooth helped this misidentification take hold.
It was ignored for decades untilRalph 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 ahypsilophodont orturtle. Professional opinion has not changed much since then, although based on size, it appears more likely to be aniguanodont than a hypsilophodont.[10] Reviews either put it at Ornithopodaincertae sedis[10] or Iguanodontia.[4][5] Oddly, a semipopular reference reassigned it toGenyodectes without comment,[15] a view which has not been followed since.
Coria estimates the size of theLoncosaurustype individual at about 5 m (16.4 feet) long.[10] As a small to medium-sized ornithopod, it would have been an agilebipedalherbivore.[5]
