Stegosaurus (; lit. 'roof-lizard') is a genus of herbivorous, four-legged, thyreophorans from the Late Jurassic, characterized by the distinctive upright plates along their backs and spikes on their tails. Fossils of this dinosaur have been found in the western United States and in Portugal, where they are found in Kimmeridgian- to early Tithonian-aged strata, dating to between 155 and 150 million years ago. Of the species that have been classified in the upper Morrison Formation of the western US, only three are universally recognized: S. stenops, S. ungulatus and S. sulcatus. The remains of over 80 individual animals of this genus have been found. Stegosaurus would have lived alongside dinosaurs such as Apatosaurus, Diplodocus, Brachiosaurus, Allosaurus, and Ceratosaurus; the latter two may have preyed on it.
These were large, heavily built, herbivorous quadrupeds
with rounded backs, short fore limbs, long hind limbs, and tails held high in the air. Due to their distinctive combination of broad, upright plates and tail tipped with spikes, Stegosaurus
is one of the most recognizable kinds of dinosaurs. The function of this array of plates and spikes has been the subject of much speculation among scientists. Today, it is generally agreed that their spiked tails were most likely used for defense against predators, while their plates may have been used primarily for display, and secondarily for thermoregulatory
had a relatively low brain-to-body mass ratio
. It had a short neck and a small head, meaning it most likely ate low-lying bushes and shrubs. One species, Stegosaurus ungulatus
, is the largest known of all the stegosaurians
(bigger than related dinosaurs such as Kentrosaurus
). (Full article...
Simulation of Lake Alamosa's surface, looking towards Blanca Peak
Lake Alamosa is a former lake in Colorado. It existed from the Pliocene to the middle Pleistocene in the San Luis Valley, fed by glacial meltwater from surrounding mountain ranges. Water levels waxed and waned with the glacial stages until at highstand the lake (high water level in the lake) reached an elevation of 2,335 meters (7,661 ft) and probably a surface of over 4,000 square kilometers (1,500 sq mi), but only sparse remains of the former waterbody are visible today. The existence of the lake was postulated in the early 19th century and eventually proven in the early 20th century.
The lake eventually overflowed into the Rio Grande River
system during the middle Pleistocene. The overflow cut down a valley that eventually drained the lake, leaving only the San Luis Closed Basin
as a remnant. The Alamosa Formation
is a rock formation left by the lake. Groundwater
resources are contained trapped between sediments left by the former lake. (Full article...