Episode 138 is all about Antarctopelta, a stocky, armored dinosaur.

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In this episode, we discuss:

News:

The dinosaur of the day: Antarctopelta

Name means Antarctic shield

Lived in the Cretaceous in what is now Antarctica

Hard to classify, because it had characteristics of two different families (ankylosaur and nodosaur)

Thompson and others in 2011 suggested it is the basal most known nodosaurid

Only one species: Antarctopelta oliveroi

Species name is in honor of Eduardo Olivero (found the holotype, first mentioned it in print, and worked in Antarctica for many years)

Discovered in 1986 on James Ross Island by Argentine geologists Eduardo Olivero and Roberta Scasso (they were hiking and spotted fragments)

Was the first dinosaur found on Antarctica, but the second dinosaur from Antarctica to be formally named (first one named was Cryolophosaurus, which was found in 1993)

Found in shallow marine deposits

Took almost a decade to excavate because of harsh weather and frozen ground

Holotype consists of three teeth, part of the lower jaw, skull fragments, vertebrae, partial limb bones, toe bones, and pieces of armor

Lots of bones in poor condition because they were fragmented by freeze-thaw weathering

Had been written about in previous publications (1987, 1991), but not named until 2006

Named by Leondardo Salgado and Zulma Gasparini

Medium sized, estimated to be about 13 ft (4 m) long

Stocky

Herbivorous

Had leaf-shaped asymmetrical teeth

Had large teeth compared to other ankylosaurs (largest one was 0.4 in or 10 mm across)

Quadrupedal

Six different osteoderms were found near Antarctopelta, but not many were articulated with the skeleton, so it’s unclear where they were on the body

One osteoderm is the base of a large spike

Also flat, oblong plates, similar to the ones that were around the neck of the nodosaurid Edmontonia

Also had large, armor circular plates with smaller, polygonal nodules, that may have formed a shield over the hips

Had an oval-shaped osteoderm with a keel running down the middle (found in the ribs so may have run in rows along its flank)

And had ossicles (small bony nodules) that were probably all around the body

Not much of the skull is known, but all skull fragments found were heavily ossified

One bone, a supraorbital, had a short spike that would have come outwards over the eye

Not all of the tail was found, but some of the vertebrae found probably was near the tip of the tail and they had ossified tendons, which would have stiffened the tail (probably to support a tail club, though that has not been found for Antarctopelta)

Nodosaurs do not have club tails

At first scientists thought it was a juvenile, but parts of the vertebrae were fused together (as seen in adults) so may be a subadult

Earth was warmer when Antarctopelta lived (no ice in Antarctica then)

Lived in forests with conifers and possibly deciduous trees

But still would have been dark for long periods of time in the winter

Antarctic Peninsula at this time was connected to South America, so animals could have traveled between continents (though no evidence yet of common ankylosaurs between Antarctica and South America)

Probably lived in the same area and time as ornithopods like Trinisaura

Fun Fact:

What is the difference between a Asteroid, meteoroid, comet, meteor, and meteorite?

According to the Center for Near Earth Object Studies, a division of NASA:

Comet A relatively small, at times active, object whose ices can vaporize in sunlight forming an atmosphere (coma) of dust and gas and, sometimes, a tail of dust and/or gas. (Usually from the outer solar system)

Asteroid A relatively small, inactive, rocky body orbiting the Sun. (Usually from the asteroid belt)

Meteoroid A small particle from a comet or asteroid orbiting the Sun.

Meteor The light phenomenon which results when a meteoroid enters the Earth’s atmosphere and vaporizes; a shooting star.

Meteorite A meteoroid that survives its passage through the Earth’s atmosphere and lands upon the Earth’s surface.



Some define meteoroids as pieces of comets or asteroids

Threshold between meteoroid and asteroid? Technically “significantly smaller than an asteroid and considerably larger than an atom or molecule” Typically 1 to 10m and below is a meteoroid and larger is an asteroid, but some consider the line more like 1km

According to the Lunar and Planetary Institute the Chicxulub impactor was probably an asteroid or comet 10 to 15 kilometers in diameter (6 to 7.5 miles)

Definitely too big to be a meteoroid

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