Monthly Archives: July 2021
Posted: July 30, 2021|Categories: Dinosaurs|Comments:|
Besides the ghastly and impressive shapes of dinosaurs, there’s one thing that never ceases to amaze paleontologists and the general public around the world: their gigantic size.
Take Argentinosaurus, for instance. This titanosaur had a massive size and weighed between 50 and 90 tonnes, as believed by scientists. And if you look at today’s mammals, most of them are only between 10 and 100 kilograms in weight, while only the blue whale surpasses the size of dinosaurs. No wonder people look for titanosaur teeth for sale these days.
With a difference of such magnitude between the long-gone dinosaurs and today’s mammals, it makes sense why people wonder and question: how did dinosaurs grow so big?
Let’s look at the reasons that may have caused dinosaurs to grow so big.
Large body protected dinosaurs from most predators
While it didn’t happen in a blink, dinosaurs eventually grew bigger as part of their evolution. But the reason behind their evolution can be the protection they got from having a body larger than other creatures.
Large animals are harder to hunt, so predators naturally go for smaller animals since they are easy to catch and kill. For example, if you look at elephants, their large size saves them from being attacked by most predators, including tigers, lions, hyenas, and more. The same may have been true for dinosaurs millions of years ago.
They grew in size for food
Present-day giraffes are among the largest animals on Earth. And they became large as a result of the advantage they got from their size. They can reach higher foliage that other animals can’t, allowing them to gather food.
Posted: July 26, 2021|Categories: Dinosaurs||
When trilobites emerged in the oceanic environment during the Cambrian period, they were already fully formed creatures. They had complex digestive systems, highly developed eyes, and functional calcite carapaces that were quite admirable. In other words, the most advanced life form at that moment on our planet were trilobites! While getting a well-preserved, authentic trilobite fossil is a daunting task, it is also among the most prized possession for a collector. So, we keep adding authentic trilobite fossils for sale to our selection.
Today, we will talk about trilobite eyes. It was fascinating that the creature developed a sophisticated visual system, although not the first one in the animal kingdom with eyes. But there were trilobite suborders, like Agnostina, who were primarily eyeless. The majority had compound pairs of eyes, typically placed on their fixigenas or the fixed cheek shell outer edges.
A Good Eye Design
Trilobite had crystalline lenses that were rigid and could not change shape for focusing better on objects at different distances. But they had double lenses with different refractive indices, which corrected the problem. In fact, the rigid doublet lens allowed trilobites to have a remarkable field depth (they could focus on objects that were near and far with fairly good focus). The image distortion was also minimal.
Three Types Of Trilobite Eyes
Scientists recognize three kinds of eyes in trilobites, namely, abathochroal, holochroal, and schizochroal. The last two were the predominant types. Holochroal eyes had close packing biconvex lenses, with a single corneal layer covering the entire lens. The lens is typically