Over the eons, animals have changed greatly, and there are many extinct species with living relatives. Many of these lineages have become smaller over time, and they often appear much cuter and more approachable than their prehistoric counterparts.
Sadly, all the prehistoric animals below are now extinct. We don't know exactly what their appearances were like when they were alive, so the images are best-guess reconstructions by paleontologists. Still, viewing the ancient and modern creatures side by side is a thought-provoking experience that reminds us of the power of natural selection to shape living forms.
Fossils of extinct prehistoric giant owls that preyed on smaller owls have been discovered in a cave in Ecuador. The prehistoric owl, Asio ecuadoriensis, lived 40,000 years ago, with a wingspan of about 5 feet, and a height of more than 2.3 feet. Researchers from the Laboratorio de Anatomía Comparada y Evolución de Vertebrados of the Museo Argentino de Ciencias Naturales (LACEV-MACN) and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) also found the bones of smaller owls in the cave. The bones appeared to have signs of decay from stomach acid, suggesting the smaller owls were prey of the larger one, which didn't show such decay.
"One of [the larger owl's] peculiarities is that, apparently, it had a predilection for consuming other smaller owls," said Dr. Federico Agnolin, co-author of the study published in the Journal of Ornithology. "It is a biological rarity." Asio ecuadoriensis, he said, "was practically what could be called a cannibal owl.”
Dolphins are sweet little cetaceans, right? Well, they haven't always been that way. A giant extinct dolphin that lived from around 23 million to 40 million years ago during the Oligocene Epoch behaved a lot like a killer whale. According to a study published in the journal Current Biology in July 2020, scientists who examined a nearly complete rare skeleton of an Ankylorhiza tiedemani dolphin found in South Carolina said the animal "was a macrophagous [feeding on large particles] predator that could swim relatively fast, indicating that it was one of the few extinct cetaceans to occupy a niche similar to that of killer whales."
According to a news release about the study, features of the 15-foot-long cetacean's skeleton including its skull, teeth, flipper, and vertebrae indicate that the dolphin (dolphins are toothed whales) was "a top predator in the community in which it lived" and that modern whales "must have evolved similar features independently, driven by parallel evolution in the very similar aquatic habitats in which they lived."
Researcher Robert Boessenecker of the College of Charleston in Charleston, SC, said whales and dolphins "have a complicated and long evolutionary history... The fossil record has really cracked open this long, winding evolutionary path, and fossils like Ankylorhiza help illuminate how this happened."
On May 13, 2020, scientists published an analysis in The Royal Society journal about the fossilized remains of a 3-foot-long saber-toothed fish that is anatomically similar to modern anchovies. The fish, named Monosmilus chureloides (which translates to "single knife Churel," after a shape-shifting demon from South Asian folklore), lived about 45 million years ago in Pakistan, and had 16 fangs on its lower jaw that, according to lead researcher Alessio Capobianco, became "progressively larger towards the front."
On the ancient animal's upper jaw is a giant curved fang that resembles a saber tooth, which implies the creature was a saltwater predator.
Crocodiles are scary enough as is. But imagine a giant crocodile over 36 feet long! The sarcosuchus is often referred to as the '"supercroc" due to its enormous size. Also, this prehistoric crocodile could live over 40 years, while many crocodiles today only live to be 25 years old.
Other than being much larger, the sarcosuchus, which lived approximately 112 million to 94 million years ago, resembled modern crocodiles. It had a longer, skinnier snout, but other than that, its body was structured fairly similarly.
The sarcosuchus isn't the only ancestor to modern crocs, however. An international team of researchers was able to trace how the aquatic thalattosuchians adapted to life at sea by examining the changing shapes of their inner ears. According to a study published in the Proceedings of the National Academy of Sciences in April 2020, the Jurassic-era relatives to crocodiles left behind a fossil record that revealed they may have survived in the deep sea as opposed to shallow waters.