A Long, Long Time Ago Trivia Quiz

Answer: The first eukaryotes

Eukaryotes? Those would be cells that have a nucleus as well as other membrane-bound organelles. They most likely came about when prokaryotes tried unsuccessfully to digest other prokaryotes, which became organelles over time. This is believed to be the reason that mitochondria have their own DNA.

It is a little difficult to tell when the first eukaryotes arose as, after all, we're talking about microscopic life on a scale of billions of years ago. Nonetheless, most sources suggest the later Paleoproterozoic as our best guess.

Answer: Sexually-reproducing red algae

Multicellular life can be found as far back as the Mesoproterozoic or possibly the Paleoproterozoic period. It's difficult to tell -- and it is known to have evolved numerous times as well. Red algae is among the oldest multicellular life forms, and the 1.2-billion-year-old Bangiomorpha pubescens from Canada are the earliest example that we know of sex: they had male and female spores. All organisms that reproduce by sex had a common ancestor, and red algae may have been it, or close to it.

Answer: Paleophragmodictya, oldest sponge

Discovered in Australia in 1996, Paleophragmodictya is commonly described as the oldest probable sponge and thus one of the first animals. Fossils have been dated in the neighborhood of 570-650 MYA. This particular species is classified as a Hexactinellid, better known as a glass sponge. Sponges are believed to have achieved their greatest diversity far later -- in the Cretaceous -- and are probably not disappearing from Earth any time soon.

Answer: Olenellid, an early trilobite

The easily-recognizable trilobites were one of the most successful critters in Earth's existence, and stuck around for about 270 million years. Trilobites are considered arachnomorph arthropods and have a pillbug-appearance to them, though the closest living animals to them are chelicerates, like horseshoe crabs. Across their existence, species ranged from 1 mm to 27 cm (28 in) in length.

The last trilobites died out during the extinction event of the Permian, 252 MYA.

Answer: Oldest crinoids (sea lilies)

Despite the name, sea lilies are animals. They are related to the likes of starfish and sea urchins, and show a five-line symmetry and a water vascular system. Fossils of their stems are quite common; the longest-known crinoid stem is 40 m (130 ft) long, longer than any animal alive today. Crinoids survived multiple extinction events and some species still exist today.

The Ordovician was a time of shallow seas and diversification. Many different trilobites, molluscs, arthropods, and fish arose during this time.

Answer: Cooksonia, first land plant

Named after Isabel Cookson, Cooksonia are the oldest land plants and the first that are known to have vascular tissue. Most specimens of Cooksonia were first discovered in Britain but have since been found across the globe. As they were very primitive, they had no leaves, flowers, or roots.

It's been suggested that a few million years after plants reached land, they triggered a chain of events that dramatically reduced carbon dioxide levels in the atmosphere and caused an ice age, a hypothesis known as Snowball Earth.

Answer: Dunkleosteus, massive armored fish

Even by today's standards, Dunkleosteus was impressive: the largest ones could get up to 6 m (20 ft) in length. Hundreds of millions of years ago, that was absolutely monstrous. It was heavily armored with large, guillotine-like teeth and could open its jaws in a fraction of a second to create a strong suction force. Estimates on its bite force vary but all agree it was quite strong. One calculation suggests that, at its sharpest point, Dunkleosteus could bite with 80,000 PSI, making it a serious contender for strongest bite force of all time.

Answer: Meganeura, a giant dragonfly

Meganeura was essentially a giant dragonfly, with a wingspan of 70 cm (28 in) and was among the largest of all insects. As it far exceeds the size that insects can reach today from the way oxygen diffuses through their bodies, it's been suggested that Meganeura reached such enormous sizes due to a much higher concentration of oxygen in the atmosphere long ago.

Other studies suggest that insects became smaller (and more agile) when birds took to the skies and started eating them.

Answer: Dimetrodon, a reptilian synapsid

Dimetrodon is one of the most recognizable synapsids -- animals that eventually gave rise to both mammals and reptiles. Commonly mistaken for a dinosaur, Dimetrodon is reptilian (thus, a mammal-like reptile) and had a prominent sail on its back. Reaching a size of 4.6 m (15 ft), it was likely the apex predator of its time.

Its teeth grew larger and serrated over its existence, which is believed to have happened due to its prey growing larger over time. Suggestions for the purpose of its spine include heat regulation and courtship displays.

Answer: Grippia, a basal ichthyosaur

Ichthyosaurs -- the dolphin-like reptiles that swam alongside dinosaurs for hundreds of millions of years. Grippia was one of the oldest of these and appears in the fossil record during the Triassic. It is considered to be a basal ichthyosaur, as compared to the more advanced ichthyosaurs that arose later. Ichthyosaurs came about when terrestrial reptiles returned to the seas. They were viviparous, and fossils of the closely-related Chaohusaurus suggest that basal ichthyosaurs gave birth head-first, which in turn suggests that reptilian birth evolved only on land.

Answer: Megalosaurus, first dinosaur discovered

Megalosaurus, a theropod from the Jurassic period, was discovered in England as far back as the 1600s and became the first dinosaur to be recognized for what it was. Originally called Scrotum humanum, it was given its modern name in 1827. Richard Owen, who in 1842 created the name and clade of dinosaurs (Dinosauria), based his original classifications in part on Megalosaurus. Megalosaurus is also present in the highly inaccurate but historically significant Crystal Palace Dinosaurs, which generated significant public interest in dinosaurs and other ancient animals.

Answer: Quetzalcoatlus, the largest pterosaur

Pterosaurs flew the skies alongside dinosaurs for most of their existence. The largest of these, the Quetzalcoatlus, came about towards the end of the age of dinosaurs, in the Cretaceous. With a wingspan of 11 m (36 ft) or more, it was likely the largest animal that ever took to the skies.

Interestingly enough, Quetzalcoatlus and other pterosaurs are also believed to have walked on the ground on all fours. Their wings were essentially an elongated fourth finger accompanied by webbing.

Answer: Eohippus, the proto-horse

Eohippus, the 'dawn horse', was present in North America around 56 MYA and became the ancestor of horses. Additionally, it is similar to the ancestors of today's perissodactyls -- odd-toed ungulates that include horses, zebras, tapirs, and rhinoceroses.

It was only about the size of a fox and showed adaptations for running such as proportionally long limbs. For tens of millions of years, it saw little change and was a common critter in North America. Horses finally arose via the genus Plesippus, about 3.5 MYA.

Answer: Australopithecus, an early hominid

Australopithecus was a genus of hominids that arose in eastern Africa and in due time gave rise to humans. They were a fair bit smaller than modern people and had brains about one-third our size. While most are believed to have subsisted on fruit, butchered animal bones suggest that a few species ate animals and probably used simple tools.

The first Australopithecus discovered was at Taung, South Africa in 1924. The most famous Australopithecus would be Lucy, an Australopithecus afarensis discovered in Ethiopia in 1974 and known there as Dinkinesh. Several species are now recognized.

Answer: Smilodon, a saber-toothed tiger

With two very large teeth, Smilodon is difficult to forget. Smilodon was like one of today's big cats, but much more robust. They could be found in the Americas alongside American lions and American cheetahs. Thousands upon thousands of Smilodon found their demise in tar pits, and these provide an abundant source of bones and information today. Smilodon went extinct about 10,000 years ago alongside many North American megafauna including giant sloths, tortoises, horses, mammoths, and giant beavers.