A species of Bastiodon first appearing in a Fossil Pokemon Reserve on a small Alolan Island, it’s still unsure if it truly is a Bastiodon and not its own species, or if its a captive bred variant for the Park. Alolan Bastiodon seem ill-suited for Defense in comparison to the standard, and display much more aggressive behavior– the best defense is a good offense apparently. These Pokemon store electricity in their frills and use flashes to communicate with the rest of their herd. Their large crown of horns is how they conduct and release electricity– the combined shock of a defensive herd could burn down an entire jungle.
*Evolves from Shieldon when given a Thunderstone.
Back to variants finally, and this time we’re here for PokeJurassic Park, since that is a thing that actually exists. This variant is mainly based off of Styracosaurus, with a little bit of Regaliceratops thrown in.
Shieldon is a ceratopsian, a member of a group of plant-eating beaked dinosaurs that are characterized by their unique frilled skulls.
Their frills are mostly thought to have been used for armor, like Shieldon, although they also served to regulate body temperature and attract mates. Ceratopsians lived in herds, and are among the last dinosaurs to have gone extinct.
But Shieldon’s pokédex entry gives us a different insight into the world of Pokémon archaeology: how they date their fossils.
Fossils are old, and everyone knows that. The challenge lies in determining exactly how old a fossil is. Knowing when a dinosaur lived (or died) helps scientists accurately piece together the evolutionary timeline. Due to their chemical composition, fossils are difficult to date themselves, so scientists must assume the fossil was formed with the surrounding rock, and age-estimate that for their solution. In Shieldon’s case, the clay the fossil was found in was used for this. But this clay is reportedly “older than anyone knows”. What does that mean?
To determine the age of surrounding rocks, scientists use a process called radiometric dating. Radiometric dating works based on the fact that all atoms naturally decay over time. For example, you may have heard of “carbon dating”. The isotope carbon-14 naturally decays into nitrogen over thousands of years. These decay processes are typically very well understood and quantifiable through a number called a half-life. For carbon-14, the half-life is 5,730 years. This means that if you start out with some amount of carbon-14, after 5,730 years half of it will have decayed into nitrogen.
The idea behind radiometric dating is that you can use this concept backwards as well. If you measure how much carbon-14 there is in a sample compared to how much nitrogen, you can derive how much carbon-14 there must have been originally, and thus determine the age.
The tricky part then lies within the half-life. Carbon dating is almost never used for dating fossils, because it’s half-life is only 5730 years. Most fossils are on the order of a hundred million years old. If you want to confidently age something that old, you have to use chemicals with much longer half-lives, such as uranium-238 (half-life: 4.46 billion years) or potassium-40 (half-life: 1.25 billion years).
((As a cool side note, thorium, with a half-life of 14 billion years, can actually be used to determine the age of a star!))
This is why we can’t directly date fossils themselves. Fossils just don’t contain these compounds; but rock layers around them, particularly volcanic igneous rocks, do contain enough uranium or potassium to measure the age. For Shieldon, the fossil was dug out of a layer of clay. Potassium is a fairly common element in clays and tephras, so it is often used for dating clay deposits. The fact that the pokémon scientists could not determine the age of the clay is somewhat worrisome. If they were using potassium dating, they should be able to determine the age as long as it is between 100,000 and several billion years old.
The claim that the clay is “older than anyone knows” implies, to me, that they were not using potassium-40 dating but rather attempting to age it with something that has too short of a half-life.
Shieldon is a defensive, herd-dwelling ceratopsian. Pokémon scientists tried to date the fossil by measuring radioactive ratios in the clay the fossil was found in. They were not able to determine an age, because the chemical they used had too short of a half-life.