#eurypterids

My 25 years of palaeoart chronology…

Triops are incredibly fun to draw.

I've been designing some cambrian creature sticker designs these past couple weeks and it got me hooked on Eurypterids.

I made these eurypterid plushies for a fossil themed market last weekend & these 6 leftover guys are up for sale rn on my website.

Eurypterids were an order of marine arthropods present all over the world between the Ordovician and Triassic periods (467.3 million to 251.9 million years ago). Popularly called ‘sea scorpions’, this order of big scaly bugs consisted of around 250 species, varying in size from less than an inch to over 8ft long, and evidence shows some of them may have been able to go on land for short periods of time. Fossils of eurypterids are most commonly found in North America and Europe, and the species Eurypterus became New York’s state fossil in 1983 because of the large number of them found in Erie County.

"Diorama of a Sulurian Seafloor in the Carnegie Museum of Natural History (eurypterids, or, sea scorpions) An extinct species"

Jaekelopterus (Jaekelopterus spp.)

Family: Pterygotid Family (Pterygotidae)

Time Period: 410-402 Million Years Ago (Early Devonian)

The two species of extremely large aquatic arthropods in the genus Jaekelopterus are examples of Eurypterids, a group of superficially scorpion-like animals that first developed in the oceans around 467 million years ago before gradually transitioning to life in brackish estuaries and potentially large bodies of freshwater until their extinction some 251 million years ago during the Great Dying, a catastrophic extinction event at the end of the Permian period. During their roughly 216 million years on earth the Eurypterids diversified into a variety of shapes and sizes with some growing to be considerably larger than any modern arthropods, and while the smaller of the two Jaekelopterus species, Jaekelopterus howelli, was by no means small (growing to be around 80cm/2.6ft long) the larger species, Jaekelopterus rhenaniae, was quite possibly the largest arthropod to ever live, reaching lengths of up to 2.5 meters/8ft. Arthropods rarely reach large sizes, primarily due to their relatively inefficient respiratory systems (which, in the absence of lungs or a closed circulatory system, would struggle to provide oxygen to a body over a certain size) and the restrictions that come with their exoskeletons (in order to grow arthropods must shed their external skeletons and grow in a new, larger exoskeleton, and the larger the arthropod is the more nutritionally taxing the production of an exoskeleton large and strong enough to support its soft tissues would be), but fossilized remains of Jaekelopterus rhenaniae show that it was able to overcome at least one of these limiting factors: the exoskeleton on almost all of its body was extremely thin, making it much more viable for a new exoskeleton to be produced following each molt and likely having the additional effect of making Jaekelopterus rhenaniae surprisingly light for an animal of its size. How Jaekelopterus rhenaniae was able to respire efficiently despite its enormous size is unknown: it is believed that atmospheric oxygen levels fluctuated considerably throughout the Devonian period and if this was the case it is possible that it lived in a period where oxygen levels were unusually high (with the subsequent fall in oxygen levels possibly explaining its extinction), or it may be that it developed a more efficient system of gas exchange or circulation than modern arthropods, which may also explain the large size of many related eurypterid species. Based on where their fossils have been found both species of Jaekelopterus are believed to have inhabited brackish or coastal freshwater environments in what is now North America and Europe (which at the time were connected as a single continent, known as Laurasia or Euramerica) where they likely lived as relatively agile and fast-moving predators, swimming using their paddle-like hind legs and a tail-like protrusion on their last abdominal section, perceiving their environment with well-developed compound eyes and catching prey such as smaller aquatic arthropods and early jawless fishes using claw-like protrusions from their jaws, which were structurally similar to the chelicerae of modern spiders (with the only known fossil of Lechriaspis patula, an ancient cousin of modern lampreys that also inhabited Laurasia during the early Devonian, being littered puncture-wounds that match the shape and size of Jaekelopterus howelli’s chelicerae.)

--------------------------------------------------------------------------  

Prehistoric Animal of the Month - February