#tuzoia

[alphynix]

The tuzoiids were an enigmatic group of Cambrian invertebrates known mostly just from their spiny bivalved carapaces. Although hundreds of fossils of these arthropods were discovered over the last century or so, only vague fragments of the rest of their bodies have been found even in sites usually known for preserving soft tissue impressions.

…Until late 2022, when several new specimens from the Canadian Burgess Shale deposits (~508 million years ago) were described showing tuzoiid anatomy in exceptional detail, finally giving us an idea of what they looked like and where they fit into the early arthropod evolutionary tree.

Tuzoiids like Tuzoia burgessensis here would have grown up to about 23cm long (~9"). They had large eyes on short stalks, a pair of simple antennae, a horizontal fluke-like tail fan, and twelve pairs of appendages along their body – with the front two pairs at the head end being significantly spinier, and most (or all) of these limbs also bearing paddle-like exopods.

The large carapace enclosed most of the body, and was ornamented with protective spines and a net-like surface pattern that probably increased the strength of the relatively thin chitinous structure.

Together all these anatomical features now indicate that tuzoiids were early mandibulates (part of the lineage including modern myriapods, crustaceans, and insects), and were probably very closely related to the hymenocarines.

Tuzoiids seem to have been active swimmers that probably cruised around just above the seafloor, with their stout legs suggesting they could also walk around if they flexed their valves open. The arrangement of their spiny front limbs wasn't suited to grabbing at fast-swimming prey, but instead may have been used to capture slower seafloor animals or to scavenge from carcasses.

———

NixIllustration.com | Tumblr | Twitter | Patreon

[leaping-laelaps]

514 millions years ago in what will one day be known as the Emu Bay Shale (South Australia), a tiny Isoxys glaessneri encounters the hunter 'Anomalocaris' briggsi.

'Anomalocaris' briggsi was a large suspension-feeding radiodont related to the famous raptorial predator Anomalocaris canadensis. It is one of two radiodont species for which exceptionally detailed fossils of compound eyes are known. The eyes in this species are unsual for radiodonts in that they are not stalked, and protected by a small plate which was likely a modified version of the lateral carapace elements found in hurdiids. The eye morphology suggests that 'A.' briggsi was a mesopelagic species capable of inhabiting depths of several hundred meters, using its acute vision to detect planktonic prey (Paterson et al. 2020).

Isoxys was a cosmopolitan genus of stem-euarthropod in the Lower and Middle Cambrian, characterized by a bivalved shield covering its whole body, two large eyes, and a frontal pair of so-called 'great appendages' probably used for grasping food items. These appendages show similarity with both the frontal appendages of megacheirans and those of radiodonts like Anomalocaris, and its mix of derived and basal anatomical traits (such as biramous appendages but an unclerotized trunk) make it a crucial organism for understanding the early evolution of arthropods (Legg & Vannier 2013, Zhang et al. 2021).

I tried to recreate the feeling of this common yet lovely type of scene in sci-fi movies where a ship or station gets dwarfed by a gigantic object slowly emerging behind it from the shadows - the only difference is that the 'giant' eye here is only about 3 cm wide, though that was still huge for the time.

References and technical details about the reconstruction under the cut:

The soft parts of I. glaessneri are not known (except for the eyes). Trunk appendages are based on I. curvirostratus (Zhang et al. 2021). Great appendages are partially based on I. communis, which may be the adult form of I. glaessneri (Fu et al. 2012); unfortunately, the great appendages of I. communis are poorly preserved (García-Bellido et al. 2009), so frontal appendage morphology was complemented with the better-known I. acutangulus.

The Isoxys is depicted here with only 11 pairs of trunk limbs, instead of the usual 13+ (Zhang et al. 2021). Based on the assumption that the ancestral arthropod grew by post-hatching addition of segments (anamorphosis) (Liu et al. 2016), a reduced number of trunk limbs was judged appropriate given the small size of the specimen (ca. 6.5 mm) and the possible juvenile nature of I. 'glaessneri'.

References:

Fu, D., Zhang, X., Budd, G. E., Liu, W., & Pan, X. (2014). Ontogeny and dimorphism of Isoxys auritus (Arthropoda) from the Early Cambrian Chengjiang biota, South China. Gondwana Research, 25(3), 975–982. https://doi.org/10.1016/j.gr.2013.06.007

García-Bellido, D. C., Paterson, J. R., Edgecombe, G. D., Jago, J. B., Gehling, J. G., & Lee, M. S. Y. (2009). The bivalved arthropods Isoxys and Tuzoia with soft-part preservation from the Lower Cambrian Emu Bay Shale Lagerstätte (Kangaroo Island, Australia). Palaeontology, 52(6), 1221–1241. https://doi.org/10.1111/j.1475-4983.2009.00914.x

Legg, D. A., & Vannier, J. (2013). The affinities of the cosmopolitan arthropod Isoxys and its implications for the origin of arthropods. Lethaia, 46(4), 540–550. https://doi.org/10.1111/let.12032

Liu, Y., Melzer, R., Haug, J., Haug, C., Briggs, D., Hörnig, M., He, Y., & Hou, X. (2016). Three-dimensionally preserved minute larva of a great-appendage arthropod from the early Cambrian Chengjiang biota. Proceedings of the National Academy of Sciences, 113, 5542–5546. https://doi.org/10.1073/pnas.1522899113

Paterson, J. R., Edgecombe, G. D., & García-Bellido, D. C. (2020). Disparate compound eyes of Cambrian radiodonts reveal their developmental growth mode and diverse visual ecology. Science Advances, 6(49), eabc6721. https://doi.org/10.1126/sciadv.abc6721

Schoenemann, B., & Clarkson, E. N. k. (2011). Eyes and vision in the Chengjiang arthropod Isoxys indicating adaptation to habitat. Lethaia, 44(2), 223–230. https://doi.org/10.1111/j.1502-3931.2010.00239.x

Zhang, C., Liu, Y., Ortega-Hernández, J., Wolfe, J. M., Jin, C., Mai, H., Hou, X. G., Guo, J., & Zhai, D. (2021). Differentiated appendages in Isoxys illuminate origin of arthropodization. Research Square.

[beforus-for-real-justice]

Someone doxed one of the mods? Crazy! Hey Tuzoia Arthro, how's your moirail, Paleoz Lagana? Still dead? Can't believe you're using some twinky jade avatar because he reminds you somehow of that stupid loser pissblood! Lol, get gud! ;} - You Know Who <3<

< I'm just going to publish this, but only because none of it is true. >

< At last count, only two members of this blog use jade avatars, but my guess is that you're referring to Mod Frog. >

< I *know* who Mod Frog is, and you're entirely wrong. >

[michaelroofian]

Likeness of Cambrian critter finally revealed, and it looks like a taco

Thanks to soft-tissue preservation, we now know what Tuzoia, a Cambrian arthropod first discovered 100 years ago, actually looked like. from Livescience https://www.livescience.com/taco-lookalike-arthropod-tuzoia via IFTTT

[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.

[kathleenseiber]

Move Over Burgess: There's A New Cambrian Lagerstätten In Town

Move over Burgess, there's a new Cambrian Lagerstätten in town. Meet Tuzoia sinesis from the Balang Formation of southern China. 

read more

Move Over Burgess: There's A New Cambrian Lagerstätten In Town published first on https://triviaqaweb.weebly.com/

[alphynix]

Cambrian Explosion #57: Tuzoiida

What were tuzoiids?

We don't know.*

Despite hundreds of specimens having been found, and around 20 different species being described, these arthropods are an ongoing puzzle.

They're known from between about 518 and 505 million years ago, in deposits associated with tropical and subtropical regions all around the world. They had large spiny bivalved carapaces up to 18cm long (7"), shaped like an upside-down domed taco shell, with a distinctive reticulated net-like surface ornamentation – but the rest of their ecology and anatomy is very unclear.

Most fossils are just empty carapaces, which appear to have been made of unmineralized chitin. Rare examples of soft-part preservation show they had a pair of stalked eyes sticking out the front, and a pair of short simple antennae, but impressions of the rest of their bodies are fragmentary and indistinct enough to not be particularly helpful.

They may have been related to the similar-looking isoxyids, or they might have closer affinities to the pancrustaceans or possibly even the equally enigmatic thylacocephalans. 

Unless we find some better fossils with clearer anatomy, they're going to remain a mystery.

Tuzoia canadensis was one of the pointier-looking tuzoiids, known from the Canadian Burgess Shale deposits (~508 million years ago). About 10cm long (4"), its carapace was lined with many long spines, with a more prominent spiky side frill than most other species.

Its reticulated ornamentation had fairly large polygonal facets, and like in other tuzoiids this is thought to have had a strengthening function – allowing it to create a large but very thin carapace with enough structural integrity to hold its shape.

———

* Edit: As of 2022, tuzoiid soft tissues have been found! Turns out they're early mandibulates and probably closely related to hymenocarines.

———

Nix Illustration | Tumblr | Twitter | Patreon

[kathleenseiber]

Move Over Burgess: There's A New Cambrian Lagerstätten In Town

Move over Burgess, there's a new Cambrian Lagerstätten in town. Meet Tuzoia sinesis from the Balang Formation of southern China. 

read more

Move Over Burgess: There's A New Cambrian Lagerstätten In Town published first on https://triviaqaweb.weebly.com/