Jurassic Park Period Part 7

 Fauna - All the rest of it

 Insects and arachnids - There appears to have been no major extinction of insects at the Triassic–Jurassic boundary. Many important insect fossil localities are known from the Jurassic of Eurasia. The diversity of insects stagnated throughout the Early and Middle Jurassic, but during the latter third of the Jurassic, origination rates increased substantially while extinction rates remained flat. The increasing diversity of insects in the Middle–Late Jurassic corresponds with a substantial increase in the diversity of insect mouthparts. The Middle to Late Jurassic was a time of major diversification for beetles. Weevils first appear in the fossil record during the Middle to Late Jurassic, but are suspected to have originated during the Late Triassic to Early Jurassic. The oldest known lepidopterans (the group containing butterflies and moths) are known from the Triassic–Jurassic boundary. Modern representatives of both dragonflies and damselflies also first appeared during the Jurassic. Although modern representatives are not known until the Cenozoic, insects thought to represent primitive relatives of modern fleas are known from the Middle Jurassic of Asia. These insects are substantially different from modern fleas, because they lack the specialized morphology and they were larger. The earliest group of stick insects first appeared during the Middle Jurassic.

Spiders diversified through the Jurassic, and several long names of species or orders were given in the article. But to me, a spider is a spider. The oldest member of the family Archaeidae is known from the Middle Jurassic of China. Mongolarachne from the Middle Jurassic of China is among the largest known fossil spiders, with legs over 5 centimetres (2 inches) long. I know I've seen granddaddy longlegs with longer legs, but maybe they are not true spiders. It's been a long time since I had the opportunity to count their legs.

Birds - The earliest avialans (birds and their ancestors) appear during the Middle to Late Jurassic. There are some examples from China that have been postulated to have been birds, but have alternatively been found to be a separate lineage of another group of animal altogether. So not only were there birds, but also animals that may or may not have been birds.

Mammals - Mammals originated from cynodonts at the end of the Triassic. Cynodonts were a group of creatures that measured up to 1.5 metres (4.5 feet) in length, and that did include a tail. They may have eaten roots, insects, eggs, and possibly even small or infant dinosaurs. As mammals, they diversified extensively during the Jurassic. While most Jurassic mammals are solely known from isolated teeth and jaw fragments, exceptionally preserved remains have revealed a variety of lifestyles. Some were adapted to aquatic life, similar to the platypus and otters. Some members had a patagium akin to those of flying squirrels, allowing them to glide through the air. One aardvark-like mammal was likely a specialist on colonial insects, similar to living anteaters.

Early relatives of monotremes first appear in the Middle Jurassic of Gondwana. The monotremes are a group of highly specialized egg-laying predatory mammals, containing the platypus and echidnas. There are only five living species of monotreme, contained within two families.

Therian mammals, represented today by living placentals and marsupials, appear during the early Late Jurassic, represented by Juramaia, a mammal closer to the ancestry of placentals than marsupials. Juramaia is much more advanced than expected for its age, as other therian mammals do not appear until a later period.

Two groups of non-mammalian cynodonts persisted beyond the end of the Triassic. One ate insects and has a few records from the Early Jurassic. A herbivorous group of cynodonts has abundant records from the Jurassic, overwhelmingly from the Northern Hemisphere.

Sounds like life was all over the planet, much like it is today. Possibly not quite as diverse as it is today. If we could keep the herbivores out of our crop fields, it might be possible to colonize. And we should be able to hunt, to put meat on the table. I'm a little worried about that, though. If we killed the wrong mammal, would we disrupt the evolutionary trail that would result in humans?

Well, we'd never know about it. There's millions of years between the Jurassic Period and the development of anything resembling humans. There's several possibilities here, that I see. Either our colony would thrive, establishing a new timeline of humans on Earth. By the time 'modern day' came around, we may have taken off for outer space. In which case, we would either all leave and Earth would be devoid of humans. Or not everybody left, and the civilization continued strong, so Earth would have humans, even though it was a mixed-up mess as to how we evolved, showing up so abruptly in the Jurassic. Or at some point, our little piece of civilization would sputter and die, and there would be no humans any more, and who would be here to miss them? Or our civilization would die, and humans would evolve, lending a whole new meaning to the term 'Circle of Life'.

Okay, so we'll take a vote. Everybody in favor of settling down here in the Jurassic Period and establishing a colony, say 'Aye'.

Jurassic Park Period Part 6

 Fauna - Amphibians & Land Animals

Amphibians - The Early Jurassic Prosalirus is thought to represent the first frog relative capable of hopping like living frogs. Recognizable frogs like the South American Notobatrachus are known from the middle of the Jurassic. Although salamander-like amphibians are known from the Triassic, salamander ancestors first appeared during the Jurassic.

But most of the land animals mentioned were dinosaurs. Dinosaurs had morphologically diversified in the Late Triassic, but experienced a major increase in diversity and abundance during the Early Jurassic after the extinction of other reptile groups, becoming the dominant vertebrates in terrestrial ecosystems.

Theropods - Theropods are a group of dinosaurs that had hollow bones and 3 claws on each appendage. They first appeared in the Late Triassic. One group, called the Neotheropoda, persisted into the Early Jurassic. The earliest 'bird snout' members of the averostrans appear during the Early Jurassic and continue throughout the rest of that period and the Jurassic. Most theropods were carnivorous, although the unusual Limusaurus of China had a herbivorous diet, with adults having beaked jaws, making it the earliest known theropod to have converted from an ancestrally carnivorous diet. The Coelurosaurs first appeared during the Middle Jurassic, including early tyrannosaurs such as Proceratosaurus. The scansoriopterygids was a group of small feathered coelurosaurs with membraneous, bat-like wings for gliding, and records have been found from the Middle to Late Jurassic.

Ornithischians - This refers to an extinct order of mainly herbivorous dinosaurs characterized by a pelvic structure superficially similar to that of birds. Hence they were called "bird-hipped", or Ornithischia. However, birds are only distantly related to this group, as birds belong to the theropod line of dinosaurs. The Ornithischians included those known as "horn-faced", such as Triceratops, and the armored dinosaurs such as stegosaurs and ankylosaurs. There is strong evidence that certain groups of ornithischians lived in herds, possibly segregated by age. Some were at least partially covered in hair- or feather-like pelts, and there is much debate of whether these pelts may have been primitive feathers.

The earliest definitive ornithischians appear during the Early Jurassic. The earliest Ankylosauria and Stegosauria appear during the Middle Jurassic. At least some ornithischians were covered in protofeathers.

Sauropodomorphs - Sauropods are a group of "lizard-hipped" dinosaurs. They had long necks and tails, small heads and 4 huge, pillar-like legs. They became the dominant large herbivores in terrestrial ecosystems during the Jurassic. Some reached gigantic sizes, becoming the largest organisms to have ever lived on land. Bipedal sauropodomorphs continued to exist into the Early Jurassic, but went extinct by the beginning of the Middle Jurassic. Quadrupedal sauropomorphs were a hold-over from the Late Triassic. One type of quadrupedal from the earliest Jurassic of South Africa reached an estimated weight of 12 tons, far in excess of other known sauropodomorphs.

So it appears there were lots and lots of dinosaurs ambling across the landscape. I know I earlier said we would pause to look at some of the better-known dinosaurs, but I didn't realize how many episodes the Jurassic Period would take, just to give it this brief look. So I've changed my mind, and the next episode (all the rest of the fauna) will finish up the Jurassic Period before I go on to the next time period in the history of the Earth. Later on, when I've finished the Earth's prehistory, I'll find a time to take a look at various species of dinosaurs, so keep watching, because I'll get to them!

Jurassic Park Period Part 5

Fauna - Fish

I don't have as much information on the fish of the Jurassic as I had on the reptiles. So this blog might not be as long. But we'll see.

Conodonts - This is a class of jawless fish that had hard tooth-like elements. They were mentioned in the article I consulted only because they died out during the Jurassic, although not all over the globe at the same time. They had over 300 million years of evolutionary history, but only a handful of species made it into the Jurassic, and those went extinct early in the period. So they wouldn't have been plentiful in the oceans, but there might have been some, depending on what time during the Jurassic period a person was looking.

Sarcopterygii - This is a fancy name for lobe-finned fish, a class of fish whose fins are attached to their bodies by a single bone. This includes several genera of lungfish, which lived in freshwater environments in both hemispheres. Some of those lungfish are fairly closely related to lungfish now living in South America and Africa, rather than those living in Queensland. And there were some living in Asia that are not closely related to any group of living lungfish. Another group of this type of fish were the Mawsoniids, which are completely extinct now, but which lived in the oceans or fresh or brackish water.

Bony fish (Actinopterygii) were major components of freshwater and marine ecosystems. Among these were the Amiiform fish, which are represented today only by the bowfin, an elongated, eel-like creature with sharp, pointy teeth that live in slow-moving fresh water. During the Jurassic, the Amiiformes became fairly global. The pycnodontiforms were small to middle-sized fish with laterally-compressed body and an almost circular outline. They lived mostly in shallow-water sea. They had round and flattened teeth, well adapted to crush food items. Some species lived in rivers and possibly fed on molluscs and crustaceans. Although they had a large variety of representatives during the Jurassic, they are all extinct now. Teleosts, which currently make up over 99% of living Actinopterygii, appeared during the Triassic and underwent a major diversification during the Late Jurassic. The Pachycormiformes are a group of fish closely allied to teleosts. They first appeared in the Early Jurassic, and included both tuna-like predatory and filter-feeding forms. This included the largest bony fish known to have existed, with an estimated maximum length over 15 metres (45 feet).

Chondrichthyes - are fish whose skeletons are mostly made of cartilage, rather than bone. During the Early Jurassic, Hubodonts, which appear to have been primitive forms of sharks were common in both marine and freshwater settings. However, by the Late Jurassic, hybodonts were minor components of most marine communities, having been largely replaced by neoselachians, which contains all living sharks and rays. Hybodonts remained common in freshwater and restricted marine environments. Relatives of the bullhead shark, carpetsharks, and mackerel sharks all made their appearance during the Jurassic. There were also other examples of extinct and relatives of now-living sharks mentioned, so I would suppose that shark-like creatures were a regular feature in the oceans.

So there were plenty of fish in the seas.

https://en.wikipedia.org/wiki/Jurassic