Plate-footed horseshoe crabs - pteropod horseshoe crabs superfamily
Eukaryotic domain
animal kingdom
Subkingdom of eumetazoa
Ecdyanimal main phylum
Arthropod phylum
Subphylum Chelicera
Plate-footed horseshoe crabs
Plate-footed horseshoe crabs
Suborder Broadwinged horseshoe crabs
Double-capped horseshoe crab under the order
Pteropods superfamily
The pterygotoidea is the family of all erypterids, which continue to be distributed in large numbers and worldwide despite only 40 million years of existence.
Like other genera , the pterygotoidea superfamily Pterygotoidea is mostly found in the continents of Laurentia, Wallonia, Avalonia, Baltica, and the Rhine-Hercynian (errane), but unlike other members of the Silurian and Early Devonian , the pterygotoidea is also very common in other ancient continents and in Australia , Libya, Algeria, Morocco, Florida, Saudi Arabia, Spain, China and South America, fossils of the pterygotoidea superfamily Pterygotoidea have been found. The earliest fossils of the pterygotoidea superfamily Pterygotoidea also appear in the early Silurian Landovery of the Landoville period, found in Scotland, Laurentia and southern China. The mobility of the pteropod horseshoe crab superfamily makes it difficult to know where its clade originated, but it is roughly speculated that the origin of the superfamily Adelmanichae, like its relative, Adelman horseshoe crab superfamily Adelophthalmoidea, is close to the continent of Laurentia. Although little is known about how the development history of the pterygotoidea superfamily Pterygotoidea expanded the oceans, the pterygotoidea and Adelman horseshoe crab superfamily Adelophthalmoidea are probably very good swimmers, so the two clades can be scattered in different paleocontinents.
Members of the pterygotus group can and have a pair of large compound eyes , indicating that they are sight-seeking predators , with another pair of small eyeballs in the center of the head. They have six dorsal armors on their abdomen with gill operculums , and a fifth pair specialized into paddles, which swim with short pulp and tail swings simultaneously for acceleration. The pterygoid horseshoe crab is an excellent swimmer, and its limbs contribute to water stability by flapping its tail up and down. The pteropod horseshoe crabs first emerged during the Silurian period and became extinct in the early to mid-Devonian period, and are closely related to the large Rhinejecker horseshoe crab Jaekelopteru srhenaniae and the freshwater Slimeonia horseshoe crab. Fossils of pteropods have been found on all continents except Antarctica. One of the highest predators in the Paleozoic oceans, the pteropod horseshoe crab was particularly large as ambush prey, living on shallow shores and unexpectedly raiding trilobites, fish and other creatures that had just swam by by ambush in the mud and sand. Unlike other small plate-footed horseshoe crabs ( such as the mixed sea horseshoe crab Megalograptus ) , pteropod horseshoe crabs cannot leave the sea and enter land for breeding and shedding. However, pterodactylus horseshoe crabs live in fresh water, and they may migrate from the ocean to lakes to catch fish. Pterodactylpod horseshoe crab fossils are fairly common , but complete ones are quite rare , they were one of the last giant plate-footed horseshoe crabs , which later became quite small and agile , and the decline of large plate horseshoe crabs may be related to their slower speed , as they are vulnerable to attack by large shieldfish.
1. Subordinates
Hughmilleriidae
Slimonidae
Pterygotidae
2. Humiler horseshoe crabs
Hughmilleria (scientific name: Hughmilleria) lived in the Euramerica from the Arenig period of the Ordovician to the Frasnian period of the Ordovician 425 million years ago, and the genus Hughmilleria norvegia and Hughmilleria bellistriata (Silurian period) were found. Their body shape differs from other plate-footed horseshoe crabs in that the precursors are rounded , the compound eyes are longer than the margins , the chelae are medium-sized , and the pincers are small , resembling a smaller version of the pterygotus horseshoe crab. Hughmilleria has an ovate posterior oral metastoma, short and broad reproductive appendages in females and long and narrow in males.
3. Cylemons horseshoe crab
The Simoniidae family (scientific name: Slimoniidae) lived in the early Silurian (Llandovery period) to the late Silurian (Pridoli) Euramerica, unlike other members of the pterygotoidea superfamily Pterygotoidea, which inhabits the sea, salty waters or freshwater.
Maintain body size from 60 cm to 1 m or more. The precursors of the Slimoniidae family are square, with ventral eyes next to the head, a narrow posterior abdomen, an enlarged and flat anterior half of the tail segment, small teeth on the limbs but lack of scabs, a narrow heart-shaped posterior plate, and long and narrow male and female reproductive appendages.
Members of the family Slimoniidae were previously classified as Hughmilleriidae, but the Slimeoniidae are distinguished from other members of the pterygotoidea superfamily Pterygotoidea in that there are no obvious chelates but other parts of the family Pterygotoidea, and the eyes are smaller than those of other members of the pterygotoidea superfamily, but they are still larger than other plate-footed horseshoe crabs (eurypterid), Members of the family Slimoniidae have been shown to be predators with better vision, feeding on small freshwater fish such as heterocarpus.
4. Pterodactylaceae
The pterygotus (scientific name: Pterygotus), also known as the pterygotus, is the second largest known broad-winged horseshoe crab.
The pteropod horseshoe crab, the name means: "winged" because its fossil parts look like wings to the miners who first discovered it. It is an animal of the arthropod phylum Platopod horseshoe crab, one of the largest plate-footed horseshoe crabs in the Silurian period, a water-dwelling predator with a body length of more than 3 meters and sharp mouth pincers, which are related to spiders, scorpions, and horseshoe crabs. Its fossils were excavated in Europe, 438-411 million years ago, about 1.5 meters long, and are one of the largest plate-footed horseshoe crabs in the Silurian period, with sharp mouth pincers, and are related to spiders, scorpions and horseshoe crabs.
(1) Characteristics
The pteropod horseshoe crab can be up to 2.3 meters long , has a pair of distinct compound eyes , a pair of smaller eyes in the center of the head , a total of four pairs of feet , a fifth pair evolved into a paddle for paddling , and a pair of chelas to catch prey. The gills and reproductive organs are located in the dorsal part of the first six segments (i.e., the tail part).
The exoskeleton of the pteropod horseshoe crab has half-moon-shaped scales. The caudal segment is broad and has a distinct ridge along the center. The chela is large and long, with serrations on the claws and curved distal edges. The cephalothorax is trapezoidal and rounded, with compound eyes located at the anterior corners. The feet used to walk are small and long, with no thorns on the feet.
(2) Habits
Pterodactylus horseshoe crabs have a pair of large eyes, which shows that they rely on vision to catch prey. The pteropod horseshoe crab is a master swimmer and is very flexible in the water. They swim with pulp and accelerate with their tails. Its tail wiggles like a whale's tail, helping them propel through the water. Its feet can help control and stabilize its body.
The pteropod horseshoe crab inhabits shallow coastal areas and preys on fish, trilobites and other small animals. They hide in the sand and ambush to hunt their prey with their front feet. They were one of the apex predators in the Paleozoic oceans.
Unlike the tiny broad-winged horseshoe crab, the pterodactylus can leave the surface of the water to land to shed its shell or breed. They can migrate to freshwater areas, such as lakes or rivers, to feed.
(3) Fossil record
The pteropod horseshoe crab first appeared in the Silurian period but disappeared in the early to mid-Devonian. They are related to the larger Jackroop horseshoe crab and the freshwater Slimeon horseshoe crab. Fossils of pteropod crabs have been found on several continents, except in Antarctica. Their fossils are common, but intact ones are rare. The reason for their decline may be related to the slower movement when shedding.
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