#fossil echinoderm shell

[uk-fossils]

HOLECTYPUS DEPRESSUS Fossil Echinoid Sea Urchin Jurassic Cornbrash Somerset UK Authentic Specimen

This listing features a well-preserved fossil echinoid (sea urchin) of the species Holectypus depressus, collected from the Cornbrash Formation in Somerset, United Kingdom. This authentic Jurassic marine invertebrate fossil is provided with a Certificate of Authenticity, and the photo shows the exact specimen you will receive.

Holectypus depressus belongs to:

Order: Holectypoida

Family: Holectypidae

This echinoid lived during the Bathonian Stage of the Middle Jurassic Period, approximately 168–166 million years ago. The Cornbrash Formation consists of marine shelly limestones and mudstones deposited in a shallow marine, inner shelf environment that supported a diverse array of invertebrate life.

Morphological Features:

Flattened, oval test (shell) with a low dome profile

Petaloid ambulacra with finely impressed pore pairs

Oral surface flattened with distinct peristome

Smooth to lightly granulated surface, often symmetrical

These features suggest an infaunal or semi-infaunal lifestyle, with the organism likely burrowing or living on soft marine sediments.

Specimen Details:

Species: Holectypus depressus

Fossil Type: Echinoid (Sea Urchin) Test

Geological Unit: Cornbrash Formation

Geological Age: Middle Jurassic (Bathonian Stage)

Location: Somerset, United Kingdom

Depositional Environment: Shallow marine shelf, calcareous muds and shelly limestones

Family: Holectypidae

This is a fine example of a Jurassic echinoid fossil from a historically significant geological unit in the UK, ideal for fossil collectors, educators, or anyone with a passion for ancient marine life.

Scale rule squares/cube = 1cm. Please see the photograph for full sizing and condition.

All of our Fossils are 100% Genuine Specimens & come with a Certificate of Authenticity.

[prasemvanguardgerman]

Fossils in white # 2

We have here some fossils on white stone.

Seashell rock imprint, and sea urchins from the echinodem genus probably.

The larger stone is chalk, limestone from the cliffs of Denmark, the echinodem of white flint stone with minimal crystallisation.

Correction of fact are welcome allowed.

[bestanimal]

Round 3 - Chondrichthyes - Heterodontiformes

(Sources - 1, 2, 3, 4)

While several extinct genera of Heterodontiformes are known from the Jurassic, today only one genus, Heterodontus, the “Bullhead Sharks” remains. Ten living species of bullhead shark have been described.

Bullhead sharks are relatively small, with the largest species reaching just 1.65 metres (5.5 ft) in maximum length. They have tapered bodies, with blunt, proportionally large heads, relatively small mouths, pig-like snouts, and pronounced ridges above their eyes. They have two large dorsal fins, the first larger than the second, and an anal fin. Both dorsal fins have a rigid spine at the front of each fin which is used for defense. Bullhead Sharks are bottom feeders in tropical and subtropical waters. They have cusped grasping teeth at the front of the mouth, and flattened teeth at the back of the mouth. They use the flattened teeth at the back of their mouth to crush hard-shelled prey like bivalves, crustaceans, and sea urchins, and the grasping teeth on soft-bodied prey like worms, anemones, and octopuses. They hunt at night by "walking" along the sea floor with alternating motions of their pectoral and pelvic fins.

Bullhead shark egg cases are shaped like an auger, with two spiral flanges. This allows the egg cases to become wedged in the crevices of rocky sea floors, where the eggs are protected from predators; however, some bullhead sharks deposit their eggs on sponges or seaweed. Due to their spiral shape, each egg case requires several hours to rotate out of the mother shark's cloaca (Oof). She usually lays two at a time. The eggs typically hatch after 7 to 12 months, depending on the species. The pups will usually reach over 14 cm in length by the time they leave the egg case.

The Heterodontiforms appear in the fossil record in the Early Jurassic, with modern forms appearing in the Late Jurassic. Despite the very ancient origins of the genus, phylogenetic evidence indicates that all living species in the genus arose from a single common ancestor that survived the K-Pg extinction.

Propaganda under the cut:

Female Japanese Bullhead Sharks (Heterodontus japonicus) are known to deposit their eggs in communal nests, with as many as 15 eggs left in the same nest.

Horn Sharks (Heterodontus francisci) (image 2) have relatively small territories they hunt in at night, returning to the same “house” during the day. They may remain faithful to the same territory for over a decade. Now that’s a homebody.

Horn Sharks are queued by light rather than by an internal clock. In laboratory settings, they will become active as soon as lights are turned off. If they are in the middle of something when the lights are turned on, they may stop swimming and sink to the bottom. In one experiment where the sharks were kept in darkness, they remained continuously active for 11 days before slowing from fatigue. (☹️)

The Horn Shark generates the highest known bite force relative to its size of any shark, which it uses to crack into mollusks, echinoderms, and crustaceans. One study found the average bite force for this species in the wild to be 95 N with a maximum of 135 N, while under experimental conditions sharks could be induced to bite with over 200 N of force.

Female Horn Sharks in the wild pick up their egg cases in their mouths and wedge them into crevices to keep them safe.

In July 2018, three people were arrested after stealing a juvenile Horn Shark from the San Antonio Aquarium. The shark was scooped out of its tank and smuggled out of the aquarium in a stroller, wrapped in a wet blanket. It was thankfully returned unharmed two days later.

The Crested Bullhead Shark (Heterodontus galeatus) (image 4) produces spiral-shaped egg capsules that are secured to seaweed or sponges with long tendrils.

The Crested Bullhead Shark is a major predator of the eggs of the Port Jackson Shark! Individual sharks have been observed taking the egg capsules in their mouths and chewing on the tough casing, rupturing it and allowing the yolk to be sucked out, or simply swallowing the capsules whole.

The Port Jackson Shark (Heterodontus portusjacksoni) (image 1) is a migratory species, traveling south in the summer and returning north to breed in the winter. Males tend to arrive to the breeding grounds first with the females arriving later and staying later, perhaps as a means to reduce egg predation upon their newly laid eggs.

While juvenile Port Jackson Sharks are not particularly social, adults are often seen resting in caves in groups, and prefer to associate with specific sharks based on sex and size. In lab settings, these sharks were shown to have unique personality traits and preferences, can be trained, can count, and can learn by watching other sharks.

[forgottensibiria]

Amphibian Perucetus and giant scissor sharks

In previous posts, we considered Moropiton and Poseideongenia, two groups of animals that migrated to Siberia through the Ural Sea in the Late Carboniferous. Before moving on to the actual descendants of these Seymouries - the Angarians themselves - we can distract ourselves with the creatures that the Moscow settlers could encounter on a vegetable raft.

The Dynasty of marine amphibians

Let's start with a strange speculative kind that shouldn't exist. Ichthyocetus, the "whale fish", is a large animal reaching a size of up to 2.5 meters and is a direct descendant of tetrapods of the Moscow Sea, primarily tulerpeton. The latter is known primarily for its six-toed limbs developed relative to other modern tetropods, as well as for its location. The fact is that the remains of the tulerpiton were located 200 kilometers from the supposed shore: this and the very structure of the body of the tetrapod under discussion suggest that the animal lived in shallow water, breathing atmospheric air (no bones corresponding to the gills were found, and the head was separated from the body - i.e. the tulerpeton could lift its head) and moving forward using the legs, pushing them off the bottom (their strength would not be enough to allow the toolerpeton to move on land). It is possible that some tetrapods could have stayed in this habitat, becoming the main predators of shallow waters, where larger predators like eugeneodonts or placoderms could not move normally.

Tulerpeton, 360 m.y.a. Art by Dmitry Bogdanov

Tulerpeton found fossils

Ichthyocetus is the last representative of this hypothetical clade, whose population was almost completely destroyed by the decline in sea level due to the new peak of the Karoo ice Age. His basic diet is benthos, which he can find in the buried ground: echinoderms, starfish and lilies, as well as, if luck smiles, the corpses of marine animals that the surf brings. He could also purposefully hunt for moropitons if they swam too deep. The bones of ichthyocetus are incredibly dense; this allows it to stay in the water during strong waves. This animal is able to sense the approach of a storm - then it tries to find the shore and crawl out onto it, burrowing into the sand; then they are most vulnerable. If it is impossible to find the shore, then the ichthyocetuses go to depth, swallowing air, where they can stay for 3-4 hours. Sometimes this tetropods go deep in search of new food sources, where they can catch young eugeneodonts or small fish. Surprisingly, ichthyocetuses are not the largest representatives of their clade (let's call it Ichthyocetusae): some species could grow up to 3 meters and lead a more pelagic lifestyle.

They usually appeared during periods of intense glaciation with a reduction in their original habitat. Unfortunately, this time climate change has become insurmountable.

Something about scissor sharks

If the meeting of protoseimurians with their "cousin" was unreliable, then the same cannot be said about eugeneodonts. The largest animals of the sea were the edestus, or protopirates. Although the largest protopirate species, E. vorax, could reach 6 meters (making it the largest predator of its time), the Moscow species were somewhat smaller and reached a maximum of 4 meters. These sizes correspond to the modern white shark and mako shark.

Edestus, 313—307  m.y.a. Art by Dmitry Bogdanov

Comparison of the four species of Edestus. Authors of this illustration is Leif Tapanila and Jesse Pruitt

Both poseideonogenes and moropitons encountered these cartilaginous fish - most likely, they were four-meter E. heinrichi and E. triserratus commensurate with ichthyocetus. Most likely, the edestus hunted numerous nautiloids and other soft-bodied prey and could well attack rafts, mistaking them for a dead cephalopod with a spiral shell. The protoseimuria themselves would not be of interest to the edestus - they are too small. That's what saved them.

[covenawhite66]

The worms correspond to the new genus and species Anguiscolex africanus, and the new species Wronascolex superstes.

The soft shell worms appear less than the harder shell worms in the fossil record. Also the location was in the Ocean under turbulent waters. A hostile environment for fossils.

The worms are are two to three times larger than the global record of palaeoscolecids in Australia, North America, and Central-Western Europe.

Discovery of two new palaeoscolecid taxa, the new genus and species Anguiscolex africanus and the new species Wronascolex superstes.

The Late Ordovician Tafilalt Biota of the Moroccan Anti-Atlas includes a diverse range of soft-bodied organisms, including palaeoscolecids, paropsonemid eldonioids, graptolites and cheloniellid arthropods, as well as a rich assemblage of mineralised taxa, among them conulariids, trilobites and echinoderms, often found as articulated skeletons.

[earthstory]

lymeregisfossils

130 million year old sea 🌊 urchin fossil find , I plucked from some chert bed ! Is it a nest?  it’s not just plain ! It’s a herd of sea urchins again . See more of my Jurassic 🦕Coast  fossil finds

@brandonfossils

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[alphynix]

Strange Symmetries #04: Even More Echinoderms

Early echinoderms seem to have gone through an asymmetrical phase before starting to evolving their characteristic radial symmetry. The first truly radial forms had three-way symmetry, but soon a group called the edrioasteroids upped that count to five.

First appearing in the fossil record around 525 million years ago in the early Cambrian, edrioasteroids were mostly shaped like discs or domes, and were immobile filter-feeders that lived permanently attached onto surfaces like the seafloor or the shells of other animals. Unlike most modern echinoderms their pentaradial symmetry was actually created by taking a tri-radial body plan and forking two of their arms near the bases to create a total of five.

Thresherodiscus ramosus was an unusal edrioasteroid that lived in the shallow seas of what is now central Canada during the late Ordovician, around 460-450 million years ago. Up to about 4cm in diameter (~1.6"), its arms split additional times at irregular intervals, creating a complex asymmetrical branching pattern across its upper surface.

The tips of its arms protruded slightly over the rim of its body, and along with the erratic extra branching this may have been an adaptation to increase its food-gathering surface area.

———

Another group of early pentaradial echinoderms known as the blastozoans were characterized by erect feeding appendages called brachioles. But some blastozoans abandoned their five-way symmetry in favor of much stranger arrangements, sometimes having as few as two arms – and, in some cases, two mouths.

Known from the same general area and time period as Thresherodiscus, Amygdalocystites radiatus was part of an Ordovician-to-early-Silurian lineage known as paracrinoids, which attached their irregularly-shaped bodies to the seafloor via a stem.

About 5cm long (~2") Amygdalocystites had just two asymmetric arms forming "food grooves" along its upper edge, each lined with numerous long brachioles along just one of their sides. It probably orientated itself so its body was facing down-current, which would have created eddies that brought suspended food particles within easier reach of its brachioles.

———

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[shadyufo]

Here are a few of my favorite fossils I found in the creek last year. Ones I don’t think I’ve already shared photos of, at least! 

Found tons of awesome crinoids (stems and bases), brachiopods and other shells, a mystery fossil I haven’t IDed yet (2nd & 3rd photos; likely a section of some type of echinoderm), and the only two blastoid fossils I've ever found down there! Neither is complete but it’s still a treat to find something you don’t usually see and it inspires hope to find a nice, whole specimen some day!

[dragonthunders01]

As many know well the Cambrian is the beginning of our world’s biodiversity, is an advance follow up of the ediacaran flourish of life under the ocean, the major period of life diversification with the explosion and rise of the many major clades of animals that would establish for the next 500 million years, such as mollusks, annelids, arthropods, chordates, etc. as well alongside them some other very bizarre clades that arose and at the same time perished in that span which couldn’t leave any descendant after. The marine life grew up and became more from the pacific sessile or slow filter feeders or detritivorous ediacarans stuck in the sand, radiating into a crazy mosaic of different creatures nothing like anything that appeared before and establishing the bases for the dominant clades today, with different shapes, number of legs, numbers and shape of eyes, segments, and most important… in different sizes, mostly small, but some larger than the average…

For this chart I wanted to do something more than just pick the few largest animals of period which excess the meter long (which could have been just 2 specie), so I tried to see specimen size from all other clades known from the period, giving more variety of what some of the biggest animals were, even if they weren’t gigantic like most of actual fauna, of course with this I have to be a bit selective as not many clades really became enough large, at least in this chart the species I will expose are larger than 10 cm and noticeable enough, so even the largest animals of some clades here will be out for being very, very small…

The world in this point was pretty much the world of the Panarthropods, the major clade that includes all known Arthropoda and stem-arthropod, and there is no doubt that the Lobopodians were one of the major faunistic Panarthropods in many pelagic and benthonic niches, becoming some species iconic for its many bizarre forms and some others for their extraordinary sized, specially the Anomalocarids such as the iconic genus Anomalocaris with known specimens reaching lengths of around 60 cm to a meter long making it one of the biggest predators of the ocean at the period and being the first apex predator of history; there is also a tentative competitor for the position as the biggest lobopodians, as well the biggest animal of the period, the species Omnidens amplus (originally classified as a worm), only know by a preserved set of mouthparts, which scaled up with some relatives like the benthonic dweller Pambdelurion gives a size estimation of 1.5 to 2 meters long, but for the lack of a complete body makes difficult a properly size estimation.

Alongside the Lobopodians were also the myriad species of Arthropods, most of them were in the genesis of the clades that could come up millions of years after, just like Crustaceans, Chelicerata or Mandibulata, but in this point on time these weren’t yet a thing like they would be in next periods, instead the diversity of these was formed by other clades, specially a lot of stem-group outside euarthropods and still unknown to link clades as well others euarthropods unrelated to the major clades mentioned first; the pelagic Tuzoiid Tuzoia sp. was able to reach 18 cm long, the benthonic Sidneyia inexpectans with specimens reaching up 16 cm long and  the genus Branchiocaris pretiosa which reached up sizes around 15 cm long, not giants but still pretty large among their groups.

The Trilobites are one if not the major clade of arthropods for excellence during the Paleozoic, with different variety of species, being the Cambrian the pinnacle of its population clades with more than 60 families, most of these were around the lengths of less than 10 cm and often were the prey of bigger animals, but in some others places they were able to reach a very extraordinary size, being one of the biggest species known the redlichiide Acadoparadoxides briaerus from morocco, with specimens reaching up 45 cm long. Apart of trilobites, there were some other relatives which belongs to a major clade known as “Trilobitomorpha” which resemble them in certain anatomical features, but they weren’t true trilobites, such as the Helmetiid Helmetia expansa, a very large soft-bodied looking arthropod of around 27 cm long is one of the largest non-anomalocarids arthropods of burgers shell, and the Tegopeltidae Tegopelte gigas with a size of 19 cm.

The Archaeopriapulida (stem-priapulids) were other of the predatory benthonic animals of the Cambrian landscape, pretty much found burrowing in the sand and mud and protruding from their places, exposing a large proboscis they were mostly ambush hunters. The most well known is probably Ottoia for the common of its specimens, but these often doesn’t pass the length of 8 to 15 cm, but others were bigger that this one, a good example is the species Louisella pedunculata, which the largest specimen reached a size of 30 cm long with the proboscis extended.

One odd group among the Cambrian biota was the Vetulicolians, an enigmatic clade probably related to deuterostomes. These were weird arthropod-looking creatures that shown adaptations for pelagic lifestyle and mostly being filter feeders, many of these tended to be average lengths less than 10 cm, but Yuyuanozoon magnificissimi from comes to be the largest species known, with a length of 20.2 cm

The Chordates diversity during the Cambrian was formed by a small group of vermin agnatha forms, mostly swimming filter feeding of small size of few centimeters, the largest of these was Metaspriggina with specimens reaching up to 10 cm long which wasn’t that large size compared to many Cambrian lifeforms, was still an outstanding length compared to other of the chordates of the period.

Echinoderms were in their early genesis of its diversification with some unique morphology, so bizarre and alien compared to our actual species, as well there were others similar or very close in many aspect to actual ones, although most were very minuscule, some of the few macroscopic forms included, Lyracystis which is the largest eocrinoid with specimens reaching up sizes to 21 cm tall being half of it the arms.

Lophotrochozoa flourished during this period, evolving into the important clades including the very common brachiopods, the basic annelids and the Mollusks, although there were some species that could be classified as the last ancestors or stem-relatives of such clades, they don’t belong to these clades but they are coming to the roots of these, including Odontogriphus which specimens were able to reach up sizes around 12 cm long. Mollusks started their slow path into diversification with early small shelled varieties, most of them minuscule and don’t reaching up few centimeters of length, although few reached some considerable size for the average, such as the pelagic Nectocaris pteryx, the enigmatic cephalopod-like mollusk (?) with specimens reaching up sizes of 7 cm long.

Cnidaria are among the oldest animals on earth which during the cambrian expanded though the warm oceans either as jellyfish or small coral-like forms that could spread in the next periods, among some of these early species there was Echmatocrinus  which is a pretty robust form with a height of 18 cm tall.

Sponges were one of the major reef builders of the Cambrian, forming alongside other sessile lifeforms extensive biomes which thrived in the warm swallow oceans. Some of the biggest sponges found so far belong to the species Quadrolaminiella diagonalis which were barrel shaped sponge from the Chengjiang Fauna, with a height of 20 cm and a diameter of around 12 cm. Another species was Leptomitus, a very tall but thin kind of sponge from Burgers Shale, with specimens reaching up heights around 36.4 cm, but with a diameter less than a centimeter long.

A minor stuff worth to mention, other of the bizarre benthonic reef builders that dominated the Cambrian seabed were the archaeocyathids, a group formed by small conical shaped forms with some brachiating forms, similar in many ways to sponges except in inner structure, some of these often reached sizes of around 9 to 10 cm tall and some centimeters in diameter, but according to some mentions in websites and papers some were able to reach up even very larger sizes, with giant specimens reaching around 60 cm, but I wasn’t able upon this date to locate these very big forms so I couldn’t add them (either these are exaggerated estimations from fragmentary individuals or actually those were hinted from other fossil sponges)

References

-Briggs, D. E. (1972). Anomalocaris, the largest known Cambrian arthropod. Palaeontology, 22(3), 631-664.

-Vinther, J., Porras, L., Young, F. J., Budd, G. E., & Edgecombe, G. D. (2016). The mouth apparatus of the Cambrian gilled lobopodian Pambdelurion whittingtoni. Palaeontology, 59(6), 841-849.

- Xianguang, H., Bergström, J., & Jie, Y. (2006). Distinguishing anomalocaridids from arthropods and priapulids. Geological Journal, 41(3‐4), 259-269.

-Whittington, H. B. (1985). Tegopelte gigas, a second soft-bodied trilobite from the Burgess Shale, Middle Cambrian, British Columbia. Journal of Paleontology, 1251-1274.

-Bruton, D. L. (1981). The arthropod Sidneyia inexpectans, Middle Cambrian, Burgess Shale, British Columbia. Philosophical Transactions of the Royal Society of London. B, Biological Sciences, 295(1079), 619-653.

­-Vannier, J., Caron, J. B., Yuan, J. L., Briggs, D. E., Collins, D., Zhao, Y. L., & Zhu, M. Y. (2007). Tuzoia: morphology and lifestyle of a large bivalved arthropod of the Cambrian seas. Journal of Paleontology, 81(3), 445-471.

- Rudkin, D. M., Young, G. A., Elias, R. J., & Dobrzanski, E. P. (2003). The world's biggest trilobite—Isotelus rex new species from the Upper Ordovician of northern Manitoba, Canada. Journal of Paleontology, 77(1), 99-112.

- Daley, A. C., Antcliffe, J. B., Drage, H. B., & Pates, S. (2018). Early fossil record of Euarthropoda and the Cambrian Explosion. Proceedings of the National Academy of Sciences, 115(21), 5323-5331.

- Aria, C., & Caron, J.-B. (2017). Burgess Shale fossils illustrate the origin of the mandibulate body plan. Nature, 545(7652), 89–92.

-Walcott, C. D. (1911). Cambrian Geology and Paleontology II: No. 5--Middle Cambrian Annelids.

-Morris, S. C., & Caron, J. B. (2014). A primitive fish from the Cambrian of North America. Nature, 512(7515), 419.

-Sprinkle, J., & Collins, D. (2006). New eocrinoids from the Burgess Shale, southern British Columbia, Canada, and the Spence Shale, northern Utah, USA. Canadian Journal of Earth Sciences, 43(3), 303-322.

- Sprinkle, J., & Collins, D. (1998). Revision of Echmatocrinus from the middle cambrian burgess shale of British Columbia. Lethaia, 31(4), 269-282.

- Caron, J. B., Scheltema, A., Schander, C., & Rudkin, D. (2006). A soft-bodied mollusc with radula from the Middle Cambrian Burgess Shale. Nature, 442(7099), 159.

- Walcott, C. D. (1917). Middle Cambrian Spongiae. Smithsonian Miscellaneous Collections.

- Legg, D. A., Sutton, M. D., & Edgecombe, G. D. (2013). Arthropod fossil data increase congruence of morphological and molecular phylogenies. Nature communications, 4, 2485.

- Wu, W., Zhu, M., & Steiner, M. (2014). Composition and tiering of the Cambrian sponge communities. Palaeogeography, Palaeoclimatology, Palaeoecology, 398, 86-96.

[my-name-is-dahlia]

Dictionary (pt.cdlvi)

Words taken from inside the Hong Kong Museum of History—The Natural Environment (visited on March 25, 2019):

radiometric dating (n.) a method of dating geological specimens by determining the relative proportions of the isotopes of a radioactive element present in the sample.

placoderm (n.) any member of the extinct group (Placodermi) of primitive jawed fishes known only from fossil remains.

shellfish (n.) an aquatic shelled mollusc, e.g., an oyster, scallop, etc.

Devonian (adj.) of or relating to the fourth period of the Paleozoic era, from about 408 to 360 million years BP, between the Silurian and Carboniferous periods. During this period, amphibians and forests first appeared.

bivalve (n.) any of a group of aquatic molluscs of the class Bivalvia, with laterally compressed bodies enclosed within two hinged shells, e.g., oyster, mussels, etc.

rugose (adj.) wrinkled, corrugated.

biogenic (adj.) produced by living organisms.

brachiopod (n.) any marine invertebrate of the phylum Brachiopoda (especially a fossil one) having a two-valved chalky shell and a ciliated feeding arm.

crinoid (n.) any echinoderm of the class Crinoidea, usually sedentary with feathery arms, e.g., sea lilies and feather stars.

schist (n.) a foliated metamorphic rock composed of layers of different minerals and splitting into thin irregular plates.

[newmic]

Echinoderme fossile ou dollar de sable, oursin, invertébré marin fossilisé ou carapace de sable. Un dollar de sable, avec le motif d'indentation qui ressemble à une étoile de mer.

Fossil echinoderm or sand dollar, sea urchin, fossilized marine invertebrate or sand shell. A sand dollar, with the indentation pattern resembling a starfish.

[bestanimal]

Round 2 - Arthropoda - Thecostraca

(Sources - 1, 2, 3, 4)

Thecostraca is is a class of crustaceans, many of which have planktonic larvae which become sessile or parasitic as adults. The most well-known group are the Barnacles (subclass Cirripedia), but Thecostraca also includes the parasitic Ascothoracida, and the mysterious Facetotecta.

Facetotecta, comprising only the genus Hansenocaris, are known only from their larvae (image 3) and adults have yet to be recognized, though some scientists believe they may actually be larval tantulocaridans.

Ascothoracidans are parasites of echinoderms and cnidarians. Most genera are meso and endoparasitic (living inside the host) while some are ectoparasitic (living on the outside of the host). They are similar in anatomy to copepods, with six pairs of legs, an abdomen with four segments, a telson, and a bivalved carapace. They feed on their host via piercing and sucking mouthparts, and some more advanced species also absorb nutrients through the carapace. They are sexually dimorphic, in many cases so much so that the smaller males will live inside the larger female’s mantle cavity.

Barnacles (subclass Cirripedia) are more well-known than other Thecostracans. Adult barnacles are sessile filter feeders, except for the infraclass Rhizocephala, which are parasites of other crustaceans. Barnacles attach themselves to a surface as adults, be that a rock, the shell of a mollusc, a ship, or a large animal such as a whale. They come in two common forms: acorn barnacles which grow their shells directly on a surface (image 4) and goose barnacles which attach themselves via a stalk (image 1). Barnacles have a carapace made of six calcareous plates, with a lid made of four more plates. They attach themselves to the substrate by means of a cement gland at the base of their antennae. Eight pairs of thoracic limbs, called cirri, extend from the carapace to filter plankton from the water and bring it towards the mouth. The hairs on these limbs are very sensitive to touch, and help the barnacle sense the world around them. They also have three simple eyes (ocelli) which can sense changes in light, allowing them to close their plates quickly if a shadow is detected.

Thecostracans have nauplius larvae, characterised by a head with antennules, antennae, mandables, and a single eye, three pairs of limbs, a carapace, and a telson. Barnacle larvae are brooded by the parent until their first moult, after which they are released to swim freely using setae.

The oldest known thecostracan fossil is dated from the Middle Cambrian. Traces of the parasitic forms have been dated from the Cretaceous.

Propaganda under the cut:

Barnacles have the longest penis (relative to body size) of any living animal. You can see it in action in the above gif and in this video.

Most barnacles are not parasitic (other than hitching a ride) and usually do no harm to the large animals they attach to. An overload of barnacles tends to be a symptom of an underlying issue, such as the animal being unable to shed its skin. Non-professionals scraping or pulling barnacles off of whales and turtles often does more harm than good for the affected animal!

12th-18th Century Europeans thought that Brants and Barnacle Geese emerged, fully formed, from Goose Barnacles. Gerald of Wales claimed to have seen the birds hanging down from pieces of timber, William Turner accepted the theory, and John Gerard claimed to have seen the birds emerging from their shells. In County Kerry, until relatively recently, Catholics abstaining from meat during Lent could still eat this bird because it was considered a fish.

As filter-feeders, barnacles play an important role in the ecosystem: not only for transferring nutrients up the food chain, but also for keeping the water clean.

When a barnacle chooses its home, it produces a biological glue made of six different proteins. While the glue hardens, it accumulates limestone salts, turning into a concrete-like shell. Barnacle glue is six times stronger than any manmade glue. Scientists are trying to replicate this glue for use in the fields of engineering, construction and medicine, where it can be used as a biological sealant during or post-surgery.

[rbbox]

American lobster

American lobster

The American lobster, Homarus americanus, is a species of lobster found on the Atlantic coast of North America, chiefly from Labrador to New Jersey. It is also known as Canadian lobster, true lobster, northern lobster, Canadian Reds, or Maine lobster. It can reach a body length of 64 cm (25 in), and a mass of over 20 kilograms (44 lb), making it not only the heaviest crustacean in the world but also the heaviest of all living arthropod species. Its closest relative is the European lobster Homarus gammarus, which can be distinguished by its coloration and the lack of spines on the underside of the rostrum. American lobsters are usually bluish green to brown with red spines, but several color variations have been observed. Distribution Homarus americanus is distributed along the Atlantic coast of North America, from Labrador in the north to Cape Hatteras, North Carolina in the south. South of New Jersey, the species is uncommon, and landings in Delaware, Maryland, Virginia and North Carolina usually make up less than 0.1% of all landings. A fossil claw assigned to Homarus americanus was found at Nantucket, dating from the Pleistocene. In 2013, an American lobster was caught at the Farallon Islands off the coast of California. Its also an invasive species in Sweden and its affecting the populations of native lobster species Description Profile of the anterior part of an American lobster Homarus americanus commonly reaches 8–24 inches (200–610 mm) long and weighs 1–9 pounds (0.45–4.08 kg) in weight, but has been known to weigh as much as 44 lb (20 kg), making this the heaviest crustacean in the world. Together with Sagmariasus verreauxi, it is also the longest decapod crustacean in the world; an average adult is about 9 in (230 mm) long and weighs 1.5 to 2 lb (680 to 910 g). The longest American lobsters have a body (excluding claws) 64 cm (25 in) long. According to Guinness World Records, the heaviest crustacean ever recorded was an American lobster caught off Nova Scotia, Canada, weighing 44.4 lb (20.1 kg). The closest relative of H. americanus is the European lobster, Homarus gammarus. The two species are very similar, and can be crossed artificially, although hybrids are unlikely to occur in the wild since their ranges do not overlap. The two species can be distinguished by several characteristics: The rostrum of H. americanus bears one or more spines on the underside, which are lacking in H. gammarus. The spines on the claws of H. americanus are red or red-tipped, while those of H. gammarus are white or white-tipped. The underside of the claw of H. americanus is orange or red, while that of H. gammarus is creamy white or very pale red. The antennae measure about 2 in (51 mm) long and split into Y-shaped structures with pointed tips. Each tip exhibits a dense zone of hair tufts staggered in a zigzag arrangement. These hairs are covered with multiple nerve cells that can detect odors. Larger, thicker hairs found along the edges control the flow of water, containing odor molecules, to the inner sensory hairs. The shorter antennules provide a further sense of smell. By having a pair of olfactory organs, a lobster can locate the direction a smell comes from, much the same way humans can hear the direction a sound comes from. In addition to sensing smells, the antennules can judge water speed to improve direction finding. Lobsters have two urinary bladders, located on either side of the head. Lobsters use scents to communicate what and where they are, and those scents are in the urine. They project long plumes of urine 1–2 meters (3 ft 3 in–6 ft 7 in) in front of them, and do so when they detect a rival or a potential mate in the area. The first pair of pereiopods (legs) is armed with a large, asymmetrical pair of claws. The larger one is the "crusher", and has rounded nodules used for crushing prey; the other is the "cutter", which has sharp inner edges, and is used for holding or tearing the prey. The normal coloration of Homarus americanus is "dark bluish green to greenish brown", redder on the body and claws, and greener on the legs. This coloration is produced by mixing yellow, blue, and red pigments. Despite the rarity of strangely colored lobsters, many more of them are reported being caught. It is unclear as to whether this is an artifact of social media (i.e. it is easier to report catching a strangely colored lobster), or if it is due to a drop in predator populations. Color variants Blue Yellow An estimated one in 2 million lobsters are blue. A genetic mutation causes a blue lobster to produce an excessive amount of a particular protein. The protein and a red carotenoid molecule known as astaxanthin combine to form a blue complex known as crustacyanin, giving the lobster its blue color. In 2009 a blue lobster was caught in New Hampshire; in 2011, two blue lobsters were caught in Canada, one off of Prince Edward Island, and another in the Esgenoôpetitj First Nation territory in New Brunswick; another was caught in May 2012 off Nova Scotia. A blue lobster was caught off Pine Point in Scarborough, Maine in August 2014, and was donated to a local aquarium to join 3 other blue lobsters. Most recently, one was caught in Massachusetts off the coast of Cape Cod. Yellow lobsters are the result of a rare genetic mutation and the odds of finding one are estimated to be 1 in 30 million. Reports of yellow lobsters include one off Whaleback Island (at the mouth of the Kennebec River), Maine, on August 1, 2006, off Prince Edward Island, Canada, on June 11, 2009, one discovered in Wainani Kai Seafoods in Kalihi, Hawaii in a shipment from Nova Scotia on April 30, 2010, in Narragansett Bay off Rhode Island on July 31, 2010, and one off the coast of Black Point in Niantic, Connecticut on June 9, 2014. In July 2010, an albino lobster was reportedly caught in Gloucester. An estimated only one in 100 million lobsters is albino, entirely lacking in colored pigments. On August 28, 2010, a calico lobster with a mottled orange and black shell was reported to have been caught in Maine. Only albino lobsters are rarer, and orange lobsters such as these are a 1 in 30 million catch. Several lobsters have been caught with different colorings on their left and right halves. For instance, on July 13, 2006, a Maine fisherman caught a brown and orange lobster, and submitted it to the local oceanarium, which had only seen three lobsters of this kind in 35 years. The chance of finding one is estimated at 1 in 50 million. Many split-colored lobsters observed have been hermaphroditic chimeras, but not all. Red lobsters are the usual result of a lobster being cooked. There is a 1 in 10 million chance of catching one alive with that color. Life cycle A female lobster carrying eggs on her pleopods. Note the tail flipper second from left which has been notched by researchers to indicate she is an active breeding female. Mating only takes place shortly after the female has molted, and her exoskeleton is still soft. The female releases a pheromone which causes the males to become less aggressive and to begin courtship, which involves a courtship dance with claws closed. Eventually, the male inserts spermatophores (sperm packets) into the female's seminal receptacle using his first pleopods; the female may store the sperm for up to 15 months. The female releases eggs through her oviducts, and they pass the seminal receptacle and are fertilized by the stored sperm. They are then attached to the female's pleopods (swimmerets) using an adhesive, where they are cared for until they are ready to hatch. The female cleans the eggs regularly, and fans them with water to keep them oxygenated. The large telolecithal eggs may resemble the segments of a raspberry, and a female carrying eggs is said to be "in berry". Since this period lasts 10–11 months, berried females can be found at any time of year. In the waters off New England, the eggs are typically laid in July or August, and hatch the following May or June. The developing embryo passes through several molts within the egg, before hatching as a metanauplius larva. When the eggs hatch, the female releases them by waving her tail in the water, setting batches of larvae free. The metanauplius of H. americanus is 1⁄3 in (8.5 mm) long, transparent, with large eyes and a long spine projecting from its head. It quickly molts, and the next three stages are similar, but larger. These molts take 10–20 days, during which the planktonic larvae are vulnerable to predation; only 1 in 1,000 is thought to survive to the juvenile stage. To reach the fourth stage – the post-larva – the larva undergoes metamorphosis, and subsequently shows a much greater resemblance to the adult lobster, is around 1⁄2 in (13 mm) long, and swims with its pleopods. After the next molt, the lobster sinks to the ocean floor, and adopts a benthic lifestyle. It molts more and more infrequently, from an initial rate of ten times per year to once every few years. After one year, it is around 1–1.5 in (25–38 mm) long, and after six years, it may weigh 1 pound (0.45 kg). By the time it reaches the minimum landing size, an individual may have molted 25–27 times, and thereafter each molt may signal a 40%–50% increase in weight, and a 14% increase in carapace length. Ecology The American lobster thrives in cold, shallow waters where there are many rocks and other places to hide from predators. It typically lives at a depth of 4–50 m (13–164 ft), but can be found up to 480 m (1,570 ft) below the surface. The natural diet of H. americanus is relatively consistent across different habitats. It is dominated by mollusks (especially mussels), echinoderms and polychaetes, although a wide range of other prey items may be eaten, including other crustaceans, brittle stars and cnidarians. Lobsters in Maine have been shown to gain 35-55% of their calories from herring, which is used as bait for lobster traps. Only 6% of lobsters entering lobster traps to feed are caught. Gaffkemia or red-tail is an extremely virulent infectious disease of lobsters caused by the bacterium Aerococcus viridans. It only requires a few bacterial cells to cause death of otherwise healthy lobsters. The "red tail" common name refers to a dark orange discoloration of the ventral abdomen of affected lobsters. This is, in fact, the hemolymph or blood seen through the thin ventral arthrodial membranes. The red discoloration comes from astaxanthin, a carotenoid pigment exported to the blood during times of stress. The same sign is also seen in other diseases of lobsters and appears to be a nonspecific stress response, possibly relating to the antioxidant and immunostimulatory properties of the astaxanthin molecule. Epizootic shell disease is a bacterial infection which causes black lesions on the lobsters' dorsal carapaces, reducing their saleability and sometimes killing the lobsters. Limp lobster disease caused by systemic infection by the bacterium Vibrio fluvialis (or similar species) causes lobsters become lethargic and die. Paramoebiasis is an infectious disease of lobsters caused by infection with the sarcomastigophoran (amoeba) Neoparamoeba pemaquidensis. This organism also causes amebic gill disease in farmed Atlantic salmon, Salmo salar. Infection occurs throughout the tissues, causing granuloma-like lesions, especially within the ventral nerve cord, the interstices of the hepatopancreas and the antennal gland. Paramoebiasis is strongly suspected to play a prominent role in the rapid die-off of American lobsters in Long Island Sound that occurred in the summer of 1999. Excretory calcinosis in American lobsters in Long Island Sound was described in 2002. The disease causes mineralized calculi to form in the antennal glands and gills. These cause a loss of surface area around the gills, and the lobster eventually asphyxiates. Several reasons have been proposed for the cause of a recent outbreak of the disease. The most generally attributed factor is an increased duration of warmer temperatures in the bottom of the Long Island Sound. Taxonomy The American lobster was first described by Thomas Say in 1817, with a type locality of "Long-branch, part of the coast of New Jersey". The name Say chose – "Astacus marinus" – was invalid as a junior homonym of Astacus marinus Fabricius, 1775, which is in turn a junior synonym of Homarus gammarus. The American lobster was given its current scientific name of Homarus americanus by Henri Milne-Edwards in his 1837 work Histoire naturelle des Crustacés ("Natural History of the Crustacea"). The common name preferred by the Food and Agriculture Organization is "American lobster", but the species is also known locally as the "northern lobster", "Maine lobster" or simply "lobster". As food Global capture production in tonnes by year A cooked lobster American lobsters are a popular food. They are commonly boiled or steamed. Hard-shells (lobsters that are several months past their last molt) can survive out of water for up to four or five days if kept refrigerated. Soft-shells (lobsters that have only recently molted) do not survive more than a few hours out of water. Lobsters are usually cooked alive, which may be illegal in certain areas and which some people consider inhumane. One common way of serving lobster 'tail' (actually the abdomen) is with beef, known as surf and turf. Lobsters have a greenish or brownish organ called the tomalley, which, like the liver and pancreas in a human, filters out toxins from the body. Some diners consider it a delicacy, but others avoid it because they consider it a toxin source or dislike eating innards. A set of nutcrackers and a long, thin tool for pulling meat from inaccessible areas are suggested as basics, although more experienced diners can eat the animal with their bare hands or a simple tool (a fork, knife or rock). Eating a lobster can get messy, and most restaurants offer a lobster bib. Meat is generally contained in the larger claws and tails, and stays warm quite a while after being served. There is some meat in the legs and in the arms that connect the large claws to the body. There is also some small amount of meat just below the carapace around the thorax and in the smaller legs. Lobster traps on Long Island Sound near Guilford, Connecticut See also: Lobster fishing Most lobsters come from the northeastern coast of North America, with the Atlantic Provinces of Canada and the U.S. state of Maine being the largest producers. They are caught primarily using lobster traps, although lobsters are also harvested as bycatch by bottom trawlers, fishermen using gillnets, and by scuba divers in some areas. Maine completely prohibits scuba divers from catching lobsters (violations could result in up to a $1000 fine). Maine also strictly prohibits the landing of lobsters caught by bottom trawlers and other "mobile gear". Massachusetts offers scuba divers lobster licenses for a fee, and they are only available to state residents. Rhode Island also requires divers to acquire a permit. Lobster traps are rectangular cages made of vinyl-coated galvanized steel mesh or wood, with woven mesh entrances. These are baited and lowered to the sea floor. They allow a lobster to enter, but make it difficult for the larger specimens to turn around and exit. This allows the creatures to be captured alive. The traps, sometimes referred to as "pots", have a buoy floating on the surface, and lobstermen check their traps between one and seven days after setting them. The inefficiency of the trapping system has inadvertently prevented the lobster population from being overfished. Lobsters can easily escape the trap, and will defend the trap against other lobsters because it is a source of food. An estimated 10% of lobsters that encounter a trap enter, and of those that enter 6% will be caught. In the United States, the lobster industry is regulated. Every lobster fisher is required to use a lobster gauge to measure the distance from the lobster's eye socket to the end of its carapace: if the lobster is less than 3.25 inches (83 mm) long, it is too young to be sold and must be released back to the sea. There is also a legal maximum size of 5 in (130 mm) in Maine, meant to ensure the survival of a healthy breeding stock of adult males, but in parts of some states, such as Massachusetts, there is none. Also, traps must contain an escape hole or "vent", which allows juvenile lobsters and bycatch species to escape. The law in Maine and other states dictates a second large escape hole or "ghost panel" must be installed. This hole is held shut through use of biodegradable clips made of ferrous metal. Should the trap become lost, the trap eventually opens, allowing the catch to escape. To protect known breeding females, lobsters caught carrying eggs are to be notched on a tail flipper (second from the right, if the lobster is right-side up and the tail is fully extended). Following this, the female cannot be kept or sold, and is commonly referred to as a "punch-tail" or as "v-notched". This notch remains for two molts of the lobster exoskeleton, providing harvest protection and continued breeding availability for up to five years. Fishing boats in Yarmouth, Nova Scotia In the late 1990s and early 21st century, lobster fishing was the cause of troubles between Acadians and Mi'kmaq First Nations in the Canadian Maritimes. The Acadian economy (and identity) relied substantially on fisheries, especially lobster. In 1998, the Supreme Court of Canada ruled in favor of the First Nations and granted them unlimited rights to natural resources, based on an 18th-century treaty. The federal government tried to take licenses and quotas from the traditional fishermen, whose fishing quota had already dropped dramatically in the years before, and give them to the natives. Burnt Church, a reserve between Miramichi and the Acadian town of Neguac, was the hub of these troubles. The tension increased and decreased with each fishing season, reaching its climax in April 2003, when a riot broke in the port of Shippagan, where three native-owned fishing ships and a fish processing plant were burnt down. Since then, efforts have been made to bring Acadians and natives closer together, and the tension has slowly abated. American lobster tends to have a stable stock in colder northern waters, but gradually decreases in abundance moving southward. To manage lobster populations, more regulations and restrictions, geared towards achieving sustainable populations, are implemented gradually southward. Genetics Currently there is no published genome for the American lobster, although a transcriptome was published in 2016. source - Wikipedia Dear friends, if you liked our post, please do not forget to share and comment like this. If you want to share your information with us, please send us your post with your name and photo at RBbox.in@gmail.com. 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Echinoid immersed in weak acid for cleaning, limestone decomposing and bubbling off CO2.

_s.u.m.m.e.r.l.o.v.e_

work in progress... Mal schauen was dabei raus kommt 😍...Das ist immer ein wenig wie Weihnachten 🥰 .

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Cambrian Explosion Month #27: Phylum Ectoprocta & Phylum Entoprocta

Ectoprocts, common known as bryozoans or "moss animals", are aquatic lophotrochozoans that usually live in colonies made up of many tiny cloned zooids. The exoskeletons they build for their colonies have a range of forms, including gelatinous blobs, chitinous branches, and calcified sheets and coral-like fronds.

They're part of a sub-group of lophotrochozoans called lophophorates, closely related to brachiopods and horseshoe worms, and are characterized by having a ring or U-shaped "crown" of filter-feeding tentacles around their mouths.

Mineralized bryozoans have an extensive fossil record going back to the early Ordovician, about 481 million years ago, but they're surprisingly absent from the Cambrian – with one possible exception.

Pywackia baileyi is known from fossil deposits in southwest Mexico dating to close to the very end of the Cambrian, about 489 million years ago. It formed stem-like roughly cylindrical colonies less than 1cm long (0.4"), with a calcified exoskeleton and a somewhat irregular growth pattern, and it's unclear whether it grew upright or laying on the seafloor.

Its classification is controversial and has been questioned, instead comparing it to cnidarian sea pens, so it's not definitive proof of bryozoans being present during the Cambrian. But if it was a bryozoan it brings their fossil record back by a few million years, and it may represent one of the first members of the group to develop a mineralized skeleton. Earlier bryozoans were probably entirely soft-bodied and much less likely to fossilize, and may have been rare enough components of Cambrian ecosystems that we just haven't found any yet even in sites of exceptional preservation.

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Entoprocts are tiny filter-feeding animals similar to bryozoans, but while they're also mostly colonial they don't construct elaborate exoskeletons, instead being connected to each other by stolons. Individual zooids resemble goblets, with a "cup on a stalk" shape and a lophophore crown of tentacles, and their main distinguishing feature from bryozoans is the position of their anus – entoprocts have theirs inside their tentacle crowns near their mouths, while bryozoans' are outside it.

They're traditionally grouped together with the bryozoans, but some studies consider them to be instead be closer related to horseshoe worms, or even outside the lophophorates over with the molluscs.

Their fossil record is very poor due to their minuscule soft bodies, with the oldest undisputed specimens coming from the late Jurassic (~157 million years ago). But a few similar-looking Cambrian animals have been tentatively associated with the group as members of early stem lineages, suggesting that entoprocts' ancestry is just as ancient as that of their other lophotrochozoan relatives.

Cotyledion tylodes from the Chinese Chengjiang fossil deposits (~518 million years ago) was originally interpreted as an early echinoderm, until new fossils showed its anatomy more clearly and revealed an entoproct-like crown of tentacles and a U-shaped gut.

With a cup-shaped body on a long stalk, up to 5.6cm tall (2.2"), it was significantly larger than its modern relatives, and uniquely for an entoproct it was also covered with small oval armor plates.

It would have mostly lived attached onto hard surfaces on the seafloor like rocks and shell fragments, although a few specimens have been found on the tail-tips of the deuterostome animal Vetulicola – indicating it sometimes also settled onto the carapaces of living hosts, probably opportunistically feeding on their poop.

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Dancing brittle stars tell an ancient story of existence and dying in brutal seas

  Strangely stylish and exquisite, brittle stars are a set of starfish-like sea creatures. They exist in each coloration below the solar, and some even shine with bioluminescence in the dark.

The oceans of the sector nowadays team with approximately 2, anyone hundred species of brittle stars (scientific call “ophiuroids”), on the whole residing in deep water. But they’rahistoric creature, too.

Read more: From brittle stars develop a tree of lifestyles

We recently posted our report on a brand new genus and species of brittle famous person. Known as Teleosaster creasyi, it represents the primary brittle megastar described from the fossil report in Western Australia and lived 275 million years ago.

  The evolution of brittle stars / The Conversation. The five brittle stars that formed this discovery look like they’re dancing throughout the siltstone block on which they are fossilized, even arm-in-arm.

This large amongst brittle stars (approximate diameter of 15 cm) is extra than 10 times the scale of any recognized current brittle famous person, and is an evolutionary hangover.

It is the final regarded complete “archaic” brittle superstar, sharing a basic morphology and existence conduct with bureaucracy that first advanced in the early Ordovician term (approximately 475 million years in the past). It lived in Early Permian (Kungurian) time, about 25 million years earlier than a brilliant mass extinction occasion that marked the give up of the Palaeozoic Era. This became an important time in Earth records, whilst all of the predominant companies of marine animals evolved and a few colonized the land.

  Telecaster creasy brittle stars lived 275 million years in the past. Ken McNamara, Author supplied Our discovery is exciting because it shows that that more historical paperwork lived at the same time as today’s “current” sort of brittle celebrity that developed approximately 360 million years in the past.

These fossil brittle stars are also charming because they throw mild on one of the main using forces in evolution – predation strain.

Read extra: Sludge, snags and surreal animals: a voyage to take a look at the abyss

Ancient ocean meadows

Go again 275 million years, when Australia lay ways to the south of its gift position. The seas than have been bloodless, as the Earth had simplest just emerged from a tremendous ice age. Wild storms surged in from the west, and rancid the coast of what is now Western Australia, marine animals lived a tenuous existence.

Still, the ocean teemed with existence and supported massive meadows. But these have been now not grass meadows, nor even seagrass meadows. They had been echinoderm meadows.

Echinoderms are a set of “spiny pores and skin” sea creatures. Plant-like stalked crinoids (sea lilies) have been dominant, with stems that anchored them firmly into the silty sand. With massive cups perched at the stems, and sinuous arms catching plankton from the water, they look for all of the globals like weird, warty tulips. Crawling among them were chunky starfish as large as dinner plates.

The handiest delicate animals were the brittle stars, slinking throughout the silt on five tentacle-like hands that emerged from a vital shroud-like disc.

  Once a historical sea floor, Gascoyne Junction is observed in Western Australia. Google Maps Today the wild seas of those historic times have long past, however, the beds of silt that they churned up and redeposited now outcrop as the rock in the bed of the river at Gascoyne Junction, east of Carnarvon in Western Australia.

Known as the Cundlego Formation, these siltstones are one of the most surprising examples of echinoderm Meadows recognized everywhere in the fossil file. The fossils represent a “lifestyles assemblage”; in other words, the community was frozen in time in the very spot in which they lived, suffocated by way of sand and silt throughout a violent typhoon.

  A fossil slab gives a picture of a protracted long past ocean floor. Ken McNamara, Author supplied Predation strain

Our research has proven that these newly diagnosed brittle stars endured in excessive latitude seas, whereas the “present day” kinds occupied warmer low latitudes seas. What drove the “archaic” forms far away from the low latitude seas? In our opinion, it turned into because of predation pressure.

It has commonly been notion that echinoderms, like many other corporations of organisms, underwent primary evolutionary modifications after “the super loss of life” (because the Permo-Triassic mass extinction 250 million years in the past is every so often referred to as).

The brittle stars, although, appear to have bucked this fashion with the aid of evolving into the modern guise a great deal earlier. These forms evolved an arm morphology that turned into lots extra bendy than that inside the older paperwork. They should in all likelihood move faster, scuttling throughout the ocean ground on their extra cellular arms, and also advanced the capacity to burrow in the sand and silt.

  A current day brittle megastar, Ophiothrix speculate. World Register of Marine Species, CC BY-NC-SA The cause for the evolution of these developments turned into due, in our opinion, to the upward push in shell crushing animals at some stage in Palaeozoic instances, particularly chondrichthyan fishes (the organization consisting of sharks and rays) and Heu malacostracans (the group that includes crabs) in low latitudes.

The brittle stars with their “cutting-edge”, agile body bureaucracy had been capable of withstanding this predatory onslaught in low range seas, however, the extra lumbering ancient type turned into pushed into geographic areas in search of safe haven wherein there were fewer of those predators, in this example into high latitudes.

Interestingly, there is a current analog today in the seas around Antarctica. Here there are many echinoderm meadows, with the sea floor teeming with gradual-transferring invertebrates, along with countless brittle stars, sea urchins, and starfish.

Predation stress from shell crushers is noticeably low, although latest fears of the appearance of armies of king crabs, in all likelihood connected to the warming of Antarctica, indicates that our hypothesis is probably put to the take a look at sooner than we would have liked.

Many greater of those historic Permian echinoderm Meadows continue to be to be studied in Western Australia. This will assist us to better understand the modern patience of this ancient surroundings, and how we might also help to keep those starry meadows into the geological destiny.