Jurassic Waves chapter 1: Deadly Paradise

Period: Late Jurassic (Late Tithonian)

Date: 145,000,000 BC

Location: Central and southern Laurasian islands





The central and southern islands of Laurasia (large and small) have an environment typical of the Jurassic period. Flowering Plants are absent, yet to evolve. Instead there is a spiky cornucopia of unique flora such as Conifers, Ferns, Cycads (such as Bennettitales) and Equisetaceae (including Horsetails). The air is rippled up by the screech of Pterosaurs with the occasional groan from a distant large ground-dwelling Dinosaur (like the 52-foot-long Gravisaurian Sauropod Cetiosaurus) – though occasionally the air dances with the twitter of Avialans. The climate is humid, with seasons to match: a wet and a dry season instead of summer, autumn, winter and spring. In fact the climate on Earth is about as hot as it has ever got and the water here is a pleasant 70 degrees Fahrenheit, as opposed to the 50 degrees Fahrenheit the future Quaternary Animals of this particular land will be used to. But the most important difference of all is the sea level, which in the Jurassic is some 330 feet higher than it will be in the Holocene epoch of the Quaternary period, so vast tracts of the future continent of Europe are not land during this time but seabed. With only the highest points above water, future Europe is not so much a landmass as a huge tableau of glittering islands set in a warm, shallow sea.
In fact, from above the water the central and southern islands of Laurasia (one day to be Europe) look much like paradise, but beneath the waves lives such a fearsome collection of predators. This shallow sea is a fertile one, rich in nutrients and capable of supporting life in abundance. Nutrients are washed in off the land and, because the water is shallow, passing storms also stir up organic matter from dead Animals on the seabed (and this place sees some monumental storms). It is the perfect environment for plankton to thrive and at times the water gets so thick with these teeming microorganisms that the local Sharks can barely see past the end of their snouts. The plankton supports larger Animals such as the distinctive Ammonites and the ubiquitous Belemnoids – the latter are Squid-like Decipodiform Cephalopods with ink sacs and internal hard shells called cuttlebones.
All of this and the plentiful Bony Fish are food for the bizarre, 6.6-foot-long Hybodontiform Shark Hybodus and a whole array of sizeable marine Reptiles: long-necked Plesiosauroids such as Cryptoclidus; the big-eyed, 19.5-foot-long Ichthyosaur Ophthalmosaurus; and the extraordinary Metriorhynchus – averaging 9.8 feet long and part of the marine Thalattosuchians, which are Crocodylomorphs but totally adapted to an ocean-going lifestyle. Earlier forms of Thalattosuchian from the Early Jurassic, such as the 10-foot-long Palagosaurus, lived in freshwater, but the course of evolution has substantially modified the bodies of this suborder for a marine existence. In the case of the Thalattosuchian family Metriorhynchus belongs to, the Metriorhynchids, their forelimbs are small and paddle-like, and unlike most other Crocodylomorphs, they have lost their osteoderms. Their body shape maximizes hydrodynamy, or swimming efficiency, as does having Shark-like tail flukes. But Metriorhynchus and its kin still retain some close similarities to their fellow Crocodylomorphs: a lethal set of teeth and the trait of eating just about any prey Animal it can – Belemnites, armored Ammonites, certain-sized fast-moving fish, and even the occasional seaside Pterosaur as it swoops down to catch small fish. It can even scavenge on Plesiosaur and giant-sized fish carcasses on the seafloor. They are more particular about where they live – they like warm, salty, pelagic water and tend to favor the shallower areas no more than a couple of days’ swim from land, just like the genus's close, 3-meter-long relative Geosaurus. So as far as the Metriorhynchus are concerned, the warm, shallow waters around these islands are just about perfect.
As for the giant Holost fish Metriorhynchus sometimes scavenges the carcasses of, it is a truly great behemoth. It is Leedsichthys, one of the biggest fish to ever live, growing 52.5-98 feet long. Despite their imposing size, Leedsichthys are gentle giants, no danger to anything much larger than plankton, which they filter from the seawater with a unique system of delicate bone plates equipping the gill rakers lining their gill arches. At certain times of the year, when the water goes milky with an explosion of plankton, they cruise openmouthed through these islands in great shoals.
It would seem that a fish of this size would have little to fear from other Animals, but there are at least three vicious predators native to this area that will attack a full-grown Leedsichthys. The first two are, somewhat surprisingly, Metriorhynchus and Hybodus. In keeping with their opportunistic styles of hunting, they have been known to take bites out of live Leedsichthys as well. The third threat facing these huge Creatures is a more terrifying beast altogether: again a Reptile like Metriorhynchus, but one that is almost as large as Leedsichthys. Arguably one of the largest Earth predators, on land or in the sea, of all time: Liopleurodon.

To Be Continued