Metazoa

Trichoplax adhaerens, copyright Ana Signorovitch.

Belongs within: Opisthokonta.
Contains: Volborthellida, Porifera, Rangeomorpha, Frondomorpha, Erniettomorpha, Eumetazoa.

The Metazoa, animals, are generally multicellular and phagotrophic organisms with collagenous connective tissue uniting two dissimilar epithelia (Adl et al. 2012), though some of these features have been lost in derived parasitic forms such as Myxozoa. Relationships of the major subdivisions of animals remain contentious; classic morphology has favoured a basal, possibly paraphyletic position for sponge-grade taxa (Porifera) relative to a monophyletic tissue-grade clade (Ctenophora, Cnidaria, Bilateria). Conversely, some recent molecular studies have suggested that sponge-grade animals may be derived from tissue-grade ancestors. Also lacking tissue structure is the small, flat, amorphous marine animal Trichoplax adhaerens, which moves by means of cilia on the cell surfaces and feeds on microscopic algae by lifting the body to form a ventral cavity into which digestive enzymes are released. The body of T. adhaerens possesses two layers of epithelial cells with a middle layer of syncytial contractile fibrous cells (Adl et al. 2012).

The Arboreomorpha, Rangeomorpha and Erniettomorpha are sessile organisms known from the Ediacaran period of the late Precambrian. Some authors have united these taxa in a single grouping called the Petalonamae. Theories about the affinities of Ediacaran organisms have been heavily dependent on interpretations of their internal structure. Whereas some authors have seen them as entirely soft-bodied organisms comparable in structure to modern coelenterates, others have argued that their manner of preservation implies the presence of a leathery cuticle unlike that of any modern organism (Runnegar 2022). Authors have also disagreed whether Ediacaran taxa exhibited fed via direct uptake of food particles, or obtained nutrition osmotrophically or via endosymbiotic micro-organisms. Erniettomorpha and Rangeomorpha may be placed closer to modern tissue-grade animals by the evolution of directional, determinate growth patterns instead of the fractal growth exhibited by Arboreomorpha.

The phylogenetic relationships of a number of other fossil animal groups are also unknown. The Suvorovellidae are calcareous fossils from the uppermost Precambrian with double-walled, saucer-shaped or irregularly discoidal skeletons lacking structural elements between the walls (Glaessner 1979). The Brooksellidae are early Palaeozoic medusoid structures whose organic origins have been questioned by some authors.

Salinella: what the heck was it?
Published 29 June 2007

In 1991, Haszprunar et al. published a brief book chapter in which they listed a collection of modern animals of exceedingly uncertain relationships. Any one of those organisms would make for an interesting article—some of them have now been placed with reasonable confidence in the animal family tree. The worm-like Xenoturbella masqueraded as a mollusc for a while, but now appears to be a basal deuterostome (Bourlat et al. 2003). The also-worm-like Buddenbrockia has, rather spectacularly, been shown to be a very basal member of the parasitic Myxozoa, the least animal-like of all animals (Okamura et al. 2002). But today, I’m going to touch on perhaps the most mysterious of all Haszprunar et al.‘s subjects—Salinella salve Frenzel 1892.

Salinella salve, from Frenzel (1892).

Salinella has only ever been found once, in a saline culture derived from salt beds in Argentina (Brusca & Brusca 2003). It was described as having a unique body plan, with a single layer of cells surrounding a hollow sac, open at both ends. All cells were densely covered by cilia both inside and out, and there were longer cilia around the openings (which were the mouth and anus). Other than that, there appears to have been no distinction into organs, tissues, whatever. Salinella moved by ciliary gliding, and reproduced asexually by fission.

If this description was accurate, then the affinities of Salinella become very difficult indeed. The presence of a through-gut of sorts gives Salinella a superficially bilaterian appearance, but there is no way it could be a bilaterian. All known bilaterians are triploblastic (i.e. possess three basic cell layers, with the possible exception of mesozoans, if they are reduced bilaterians), and even the outgroup of bilaterians, whether cnidarians or ctenophores, has at least a diploblastic organisation (two cell layers). Even sponges are essentially diploblastic. If there was a monoblastic stage in the evolution of animals, as has been suggested by some authors, then it would have been very early in their history. It is possible that Salinella might represent this stage, which has inferred from the blastula stage in embryonic development (Clark 1922).

Salinella has been compared in the past to the simple animals Trichoplax and the Mesozoa. Trichoplax (generally placed in its own phylum, Placozoa) is a flattened organism with only four cell types, and has been referred to as the simplest-organised animal known (Syed & Schierwater 2002). It basically comprises an upper epithelium, a lower epithelium and a central mass of cells. Digestion occurs through the formation of a hollow underneath the lower epithelium into which the animal exudes digestive juices and absorbs nutrients. Epithelial cells are ciliated but externally only.

The Mesozoa are two groups of internal parasitic animals, the Orthonectida and Dicyemida (it is now thought quite likely that these two groups are not closely related to each other). Both have a basic structure of an outer layer of ciliated cells surrounding a central mass. In dicyemids, the central sector is a single long tube cell. In Orthonectida, the central area contains gametes. Before the formation of gametes, orthonectids are a multinucleate plasmodium without distinct cells.

Beyond the superficial similarity of undifferentiated cell layers, however, Salinella as little in common with these animals. It has long been suggested that, rather than being primitively simple organisms, mesozoans represent derived animals that have become secondarily simplified as a result of their parasitic lifestyles. For both groups, there is genetic evidence to support this (Hanelt et al. 1996; Kobayashi et al. 1999). Trichoplax has a better claim to be genuinely primitive. However, Salinella lacks Trichoplax‘s central cellular layer, and Trichoplax does not have Salinella‘s cilia on both sides of the cell. And certainly there is no similarity between Trichoplax‘s external digestion and Salinella‘s through gut.

Which brings us to the final possibility, the one that many zoologists have suspected—Salinella never actually existed. It is possible that Frenzel was mistaken in his description of Salinella‘s structure (I’ve never seen Frenzel’s original description, and I’d be interested in seeing how likely this is). Could Frenzel have actually been looking at Trichoplax-like organism? Unfortunately, unless more specimens of Salinella are recovered, we are unlikely to ever know. And if Frenzel was severely mistaken, then even if the organism he was looking at is recovered, it may never be recognised as such.

Tons of little tubes
Published 14 September 2007

It is a widely-known secret that the fossil record is heavily biased towards hard parts of organisms. Soft body parts generally rot away before they can be fossilised, and usually only a shell, a bone, a piece of wood or something else reasonably crunchy has a chance of lasting long enough to be preserved. This is why sites that do preserve soft body parts, such as the Burgess Shale, Mazon Creek or Liaoning, cause such a sensation and are so significant, because the remains they present us with are so rare.

But for the vast majority of cases, we must make do with the occassions when the fossil record is willing to throw us a bone (ha bloody ha). And while palaeontologists are sometimes able to claw a simply amazing amount of detail out of just the hard parts of an organism, sometimes the information available is frustratingly incomplete. What can you say if all you have is a tube?

Take a look at the pictures above. They look to show pretty similar organisms—indeed, if you know how to tell one from the other, you’re more than a few steps ahead of me. Yet you’ve probably guessed already that they don’t*. These are not examples of the same family—they don’t even belong to the same phylum. The shells on the left (from here) belong to molluscs (gastropods) of the family Vermetidae, while those on the right (from here) are annelid worms of the family Serpulidae. Both have adopted a fairly simple tubular habit, with little in the way of extravagant ornamentation.

*After all, why would I have brought in all the rhetoric if they did?

Were you to find a fossil example of either one of these, however, all would not be lost. Molluscs and tube-worms lay down their shells in different ways, so if you knew what to look for you could tell them apart. Once you had identified your fossil as one of the above, then you could infer a lot more about what the soft parts of the animal may have looked like. Both Vermetidae and Serpulidae are around today, and the soft anatomy of the living species has been well-studied. But there are other tubular shells in the fossil record that don’t have modern representatives. One might be tempted (and many have done so in the past) to compare them with modern tubular shells in molluscs and/or annelids. But mineralised skeletal structures have evolved independently at least in foraminiferans, cnidarians (multiple times), annelids, molluscs, bryozoans, brachiopods, echinoderms and vertebrates—it is quite believable that they may have evolved in other clades as well. So for now, most of these tubular fossils get relegated to the howling wasteland of incertae sedis (Malinky et al., 2004).

Haplophrentis, from the Smithsonian.

Hyolitha: Hyoliths (the name means “tongue stones”) are conical shells found from the Early Cambrian to the Mid Permian. The illustration above shows Haplophrentis, a member of the hyolith order Hyolithida which possessed a ventral projecting ligula and two projecting side-arms called helens (structures unique to hyolithids that, in the absence of an appropriate descriptive term, Charles Doolittle Walcott apparently named after his daughter). Members of the other order, Orthothecida, lack these structures. Both orders have an operculum closing off the main shell—retractable in Orthothecida but external in Hyolithida. The function of the helens is rather uncertain—muscle scars close to them suggest that they were quite mobile and may have been used to move the animal across the sea floor (Mus & Bergström 2005), but this seems in contradiction to their delicate structure. They may have been used to hold the animal upright on soft sea-bed. They have also been suggested as supports for an external tissue system for feeding, respiration or other nefarious purposes.

As for the affinities of hyoliths, most authors have associated them with molluscs, due to similarities in shell structure and composition. One genus of hyolith, Gompholites, preserves serial muscle scars that might indicate a segmented structure that would be inconsistent with molluscan affinities (though at least some molluscs possess/ed serial structures—viz. Neopilinida and Acaenoplax), but other hyoliths do not show such an arrangement and the features seen in Gompholites are generally interpreted as representing successive scars left by chances in the muscle attachment site as the animal grew (Mus & Bergström 2005). Some remains of hyoliths show signs of a looped gut similar to that of the modern Sipuncula (peanut worms), and some authors have suggested a relationship of hyoliths to the latter (Runnegar et al. 1975). However, more basal fossil sipunculans possess a straighter gut (Huang et al. 2004).

Tentaculitids, from here.

Tentaculitoidea (Cricoconarida): Tentaculitoids are known from possibly the Ordovician (Malinky et al. 2004—the Ordovician fossils are not definitely tentaculitoids) to the earliest Permian (Niko, 2000). The type genus, Tentaculites, was originally identified (somewhat presciently—see later) as spines of brachiopods, and the name refers to the belief that they were appendages of crinoids (Schlotheim 1820). Tentaculitoids are narrow conical fossils that are radially symmetrically along the long axis. There are two major orders—the Tentaculitida had heavier shells and were probably benthic whereas the thinner-shelled Dacryoconarida may have been planktonic (there are also a number of smaller orders that have been counted as tentaculitoids, but authors have differed on these). Tentaculites has an annulated structure (as shown in the photo), and once it was recognised as an independent animal it was interpreted as an annelid due to these. Other tentaculitoids do not all show these annulations, and authors have also suggested a mollusc affinity (Yochelson’s [1964] review of a book on tentaculitoids is extremely telling in its reference to the “molluscan-annelid question”, seemingly overlooking that there might have been other alternatives). The microstructure of tentaculitoid shells is very different from molluscs, and a similarity and potential affinity with Brachiozoa has been suggested (Herringshaw et al. 2007), though doubt has apparently been cast on whether a phoronid-style lophophorate feeding system is compatible with a planktonic life-style.

Cloudina, from Palaeos.

Cloudina: Cloudina has the distinction of being one of the earliest shelled animals to have ever existed, dating from the Ediacaran. It is constructed from a series of internested cup-shaped tubes. The affinities of Cloudina are completely obscure. In a seemingly not-yet-published manuscript available online, Miller compares Cloudina to annelid tubes, but with quite a bit of uncertainty.

Torelella, from Clausen & Álvaro 2006.

Hyolithelminthes: Hyolithelminthes are elongate phosphatic tubes from the early Cambrian. They are part of a sizable collection of phosphatic taxa from that time, though over time these forms mostly became extinct and were replaced by taxa with carbonate skeletons—today, relatively few taxa (such as linguloid brachiopods) possess skeletons of calcium phosphate. For a long time it was believed that fossils such as Mobergella represented opercula of hyolithelminthes, but these are now regarded as independent animals (Bengtson 1992). The affinities of hyolithelminthes are unknown—a recent paper apparently aligns at least one hyolithelminth genus with cnidarians but I haven’t read the paper in question (Vinn 2006).

Though this has turned into something of a major post, I could still cover many more examples of tubular problematica. Cornulitids, sphenothallids, paiutiids—the list goes on and on. But in the interests of sanity (and not wasting my entire weekend), I’ll get out while I still have my dignity.

More little tubes—not just tons but tonnes
Published 20 September 2007

When I wrote the above section, I said that I was leaving the subject while I still had my dignity. But then I remembered that I have no dignity. Besides, I remembered a couple more that I really wanted to look at. Neil from Microecos suggested that “Tubular Problematica” was a good name for a band. I beg to differ—a much better one would be “The Coleolus Effect”.

Coleolus, from Yale University.

Coleolidae: Coleolus and related taxa are found from the latest Proterozoic (McMenamin, 1985) to the early Carboniferous (Yochelson, 1999). As you can see in the picture above, they are small tapering tubes. They were most likely sessile in life with most of the tube projecting above the surface of the sediment (Yochelson & Hlavin 1985).

Despite their long stratigraphic range and despite seeming to be reasonably common, the affinities of Coleolidae are completely unknown. Yochelson & Goodison (1999) noted that, “The literature on ancient “worm tubes” is scattered and scant, specimens are uncommon, and even a well-preserved one has few diagnostic characters and virtually no aesthetic interest” (ouch!) They have often been compared to Scaphopoda (tusk shells), a recent class of infaunal molluscs with superficially similar tubular shells, and more than one member of the Coleolidae has been initially identified as a scaphopod (Yochelson 1999; Yochelson & Goodison 1999). However, the shell structure is inconsistent with a mollusc, and the single known specimen with an intact tip shows that the apex was closed, unlike scaphopods which are open at both ends (Yochelson & Goodison 1999). Yochelson & Hlavin (1985) considered Coleolus to be an annelid tube but by 1999 Yochelson was admitting that “Except for formation of a calcareous tube, there is no basis for assignment of the family to Annelida“.

Anabarites trisulcatus, from Palaeos.

Anabaritidae: I’ve saved the best for last, I can assure you. Anabaritids are known from the latest Proterozoic to the earliest Cambrian, and like Cloudina were one of the earliest animals to develop a skeleton (Kouchinsky & Bengtson 2002). What’s really cool about them, though, is what’s shown in the cross-section (a) above the side view (b)—anabaritids had triradial symmetry. Triradial symmetry is exceedingly rare in modern taxa, but was found in a small assortment of Ediacaran and Cambrian organisms that have been suggested on this basis to form a grouping known as the Trilobozoa (Fedonkin 1985). The affinities of the Trilobozoa are uncertain, but most authors interpret them as coelenterate-grade. Most interestingly, Ivantsov & Fedonkin (2002) suggested that the Conulata might have a trilobozoan ancestry. The Conulata (typified by Conularia) were a class of sessile problematica that survived until the Triassic, which would represent a significant increase in time-span for the Trilobozoa. Conularia has a four-fold symmetry, which has led most authors to interpret it as related to the modern Scyophozoa (jellyfish), but the Ediacaran Vendoconularia has a six-fold symmetry which Ivantsov & Fedonkin (2002) compared to the three-fold symmetry of Trilobozoa.

An alternative to the Trilobozoa interpretation of Anabaritidae was revived by Kouchinsky & Bengtson (2002) who interpreted anabaritids as polychaete worm tubes. This was based on the presence in anabaritids of a chevron-like wall structure, previously unknown except in serpulid polychaetes. However, there is a significant gap in time between the Cambrian anabaritids and the earliest definite serpulids in the Mesozoic. Also, many anabaritid shells preserve internal tooth-like projections that suggest that whatever animal lived in them was fixed in place – if it had been able to move back and forth in the manner of a serpulid worm, it would have probably filleted itself.

A sclerite mystery
Published 25 January 2008

Eurytholia was described in 2001 (Sutton et al., 2001) for small sclerites the authors described as “hat-like” found from scattered locations in Europe and North America. Eurytholia sclerites are more or less oblong in shape, with a central ridge running parallel with the shorter sides. The figure above from Sutton et al. (2001) shows an assortment of specimens from different angles.

As yet, no articulated specimens showing what the rest of the animal looked like have been found, but the authors were able to make some inferences about it. The sclerites were exterior rather than interior—their microstructure indicates that they were secreted from the underside only, and some specimens show evidence of having been damaged while the animal was alive. They were unlikely to have functioned as teeth due to their unsuitable morphology. They also don’t appear properly shaped to have overlapped each other. Due to the relative abundances of sclerites of different sizes, Sutton et al. suggest an “armoured slug” appearance rather like that known for Wiwaxia (reconstruction also from Sutton et al., 2001):

Personally, I can’t help thinking it looks like a headless, limbless, tail-less ankylosaurian. But the wonderful thing is that we just don’t know if Sutton et al. got it right. Their reconstruction seems plausible enough, but until we find an articulated specimen, who knows what kind of tentacled monstrosity Eurytholia might actually turn out to have been?

Typhloesus: the ‘alien goldfish’ of Bear Gulch
Published 20 June 2016
Above: Typhloesus wellsi, external appearance, and the same with major anatomical details shown. Based on figure of specimen U.M. 6027 in Conway Morris (1990).

Recently, the interwebs became all agog at the suggestion that the hitherto-mysterious Carboniferous fossil Tullimonstrum gregarium could possibly represent a vertebrate, distantly related to modern lampreys. But there are other fossil animals whose relationships remain inexplicable and one of these is another child of the Carboniferous, the so-called ‘alien goldfish’ Typhloesus wellsi.

When I announced my plan to write this post, I referred to Typhloesus as coming from Mazon Creek, the fossil deposit from whence comes Tullimonstrum. This, as it turns out, was a mistake on my part: Typhloesus actually comes from a different deposit, Bear Gulch in Montana. Bear Gulch is perhaps most famous for its fossils of early fish, such as symmoriiform sharks (the ones with the weird shoebrush headgear) and heavily armoured palaeoniscoids. Indeed, compared to other Carboniferous deposits, Bear Gulch is unusual for its preponderance of swimming rather than benthic animals. Typhloesus is represented in the deposit by a number of individuals in varying states of preservation.

In some ways, Typhloesus is more famous for what it is not than for what it is. It was one of the first body fossils found in association with conodonts, minute teeth-like fossils that had been subject to much speculation as to what sort of animal they might have come from. Initially, there was much excitement that the conodont animal may have finally been found, but it did not take very long for questions to be raised about the nature of this association. By the time Typhloesus was reviewed in detail by Conway Morris (1990), it was clear that the conodont fossils had been preserved within its gut, not its mouth, and Typhloesus was a conodont-eater rather than a conodont-bearer (it has since been found that conodont animals were eel-like chordates).

Externally, Typhloesus was a fairly simple, cigar-shaped animal, with its body laterally compressed and higher than wide. It grew to a decent size, with the largest specimens being a little under ten centimetres in length. There is no sign of eyes or any other prominent sensory structure, and so far as is known the external skin or cuticle was smooth and unornamented. The most distinctive external feature is a large ‘tail-fin’ at the rear. This fin was supported by an arrangement of criss-crossing rods or fibres, and would have been fairly stiff in life. Another pair of folds or fins ran along most of the underside of the body with a noticeable gap towards the rear. Typhloesus probably swam in a not dissimilar manner to an active modern fish, using sweeps of the tail-fin to provide thrust; the ventral fins may have provided stability and steerage. The visible line of the foregut comes to a halt slightly before reaching the front of the body, and it seems that the mouth would have been slightly ventral and contained within a ‘hood’. Though its overall conformation and known gut-contents (most commonly conodonts, but sometimes worm jaws or fish scales) suggest an active predator, I am at a loss to understand how it located its prey without eyes. Perhaps the hood contained some sort of chemical sensors in life.

When it was first found, it was thought that its overall appearance suggested a relationship of Typhloesus to the chordates. However, Conway Morris (1990) saw its internal anatomy as incompatible with this view. Fossils of this animal show a narrow foregut leading into a voluminous, sack-like midgut. Below the midgut is a pair of dark, disc-shaped organs showing a concentration of iron deposits called the ferrodiscus; though a striking element of all Typhloesus fossils, the function of this structure is completely unknown. What Conway Morris found conspicuous by its absence, however, was an anus: there appeared to be no sign of any gut structures in the rear of the animal. The gut was a blind sack, with the only way out being the same as the way in. The absence of a through-gut would be unprecedented in a chordate, or indeed in many animals except jellyfish or flatworms. Conway Morris was also unable to identify other chordate-specific structures such as muscle-blocks, gill openings or a notochord; though he confessed that the first two might be obscured by the vagaries of decay, he felt that the third at least should have left more of a sign. It was this combination of an overall fish-like appearance with a very un-fish-like anatomy that led Conway Morris to later dub Typhloesus the ‘alien goldfish’.

With the exclusion of a chordate connection as a possibility, Conway Morris found himself at a loss as to just where Typhloesus fitted into animal evolutionary history. Finned swimmers are also known among molluscs, nemerteans and chaetognaths, but Typhloesus is no more like any of these than it is like a chordate. Conway Morris felt himself compelled to declare the affinities of Typhloesus completely unknown. Personally, though, I can’t help wondering if the ‘alien goldfish’ might not be so alien after all: maybe it is a chordate. The overall similarities of Typhloesus to a chordate are remarkable; in particular, the hooded mouth is very similar to that of a lancelet. But what about that missing anus, you say? Where is that all-important butthole? To which I respond, is it really missing? Looking at the figures of Typhloesus fossils in Conway Morris (1990) (which is of course a poor competitor to Conway Morris’ ability to look directly at the fossils themselves), I see that directly below the midgut is the ferrodiscus. And directly below that is a streak running between the ferrodiscus and the animal’s venter. Conway Morris saw this structure (which he called the ‘midventral strand’) as some sort of connection between the ferrodiscus and the exterior, but could it in fact be the tail-end of the reargut? It is certainly not unknown for the anus in chordates to not be right at the very rear of the animal; in some fish (such as the scorpionfish-like Aploactinidae) it is even moved so far forward as to be almost underneath the head. And the missing notochord? Considering that despite the presence of specimens numbering in the thousands, a notochord was only announced in Tullimonstrum within the past year, maybe on that front Typhloesus could reward a second look.

Systematics of Metazoa
<==Metazoa (see below for synonymy)BJ17
|--Trichoplax von Schulze 1883HCH18, AS12 [Placozoa]
| `--T. adhaerensCV16
`--+--PoriferaHCH18
`--+--RangeomorphaR22
`--+--+--PambikalbaeHCH18
| `--FrondomorphaR22
`--+--ErniettomorphaNS93
`--EumetazoaHCH18

Metazoa incertae sedis:
Namapoikia Wood, Grotzinger & Dickson 2002WGD02
`--*N. rietoogensis Wood, Grotzinger & Dickson 2002WGD02
YaworiporaWGD02
Rosellatana jamesi Kobluk 1984NS93
Podolimirus mirusIF02, EL11
Neotricula apertaLO03
Cleisopus gloriamarisNN03
Caveasphaera costataX04
Megaclonophycus onustusX04
Spiralicellula bulbiferaX04
Eurytholia Sutton, Holmer & Cherns 2001SHC01
|--*E. prattensis Sutton, Holmer & Cherns 2001SHC01
`--E. elibata Sutton, Holmer & Cherns 2001SHC01
Dimorphoconus granulatus Donovan & Paul 1985SHC01
Jennaria pulchra Rieger 1991ZHT01
Pseudomytiloides dubiusBL78
ParastromatoporaHS02
SestromellaHS02
ChaetetopsisHS02
Poterion neptuniF79
Microcordyla asteriaeBK77
StematumeniaMK83
|--S. foetidaMK83
|--S. strobilinaMK83
`--S. variabilisMK83
Hemectyon feroxMH96
SpeophilosomaT07
|--S. koyamaT07
`--S. tottorienseT07
Lycocerus suturellusT07
Parechthistatus gibberT07
Parapodisma setouchiensisT07
ArcuphantesT07
|--A. hibanusT07
|--A. iharaiT07
|--A. saitoiT07
`--A. tsurusakiiT07
‘Leptophyllus’ Quenstedt 1876 non Hope 1842FT93
Paracharnia dengyingensisXS05
Pararenicola Wang 1982 [incl. Paleorhynchus Wang 1982]SWZ86
`--*P. huaiyuanensis Wang 1982 (see below for synonymy)SWZ86
Protoarenicola Wang 1982SWZ86
`--*P. baiguashanensis Wang 1982SWZ86
VolborthellidaWS93
Ptychoderma australiensisH09
Limnorea Goldfuss 1826BR05
AncodonS61
|--A. gorringeiS61
`--A. parvusS61
Conigalea Ivanov 1995 [Actinaculata, Conigaleidae, Conigaleoida, Marinaculata]I95
`--*C. otschevi Ivanov 1995I95
Basiliella wusungensisD82
AttungaiaF71
|--A. cloacataF71
`--A. wellingtonensis Pickett 1967F71
Columellaespongia woolomolensis Pickett 1967F71
Devonospongia clarkeiF71
Hyalostelia australis Etheridge 1916F71
Varneycoelia favosa Pickett 1967F71
Ramenta Jiang in Luo et al. 1982P08
Ernogia Jiang in Luo et al. 1982P08
Stenothecopsis Cobbold 1935F62
`--*S. heraultensis Cobbold 1935F62
Scenellopsis Resser 1938F62
`--*S. clotho (Walcott 1905) [=Scenella clotho]F62
Charruia Rusconi 1955F62
`--*C. annulata Rusconi 1955F62
Cyrtotheca Hicks 1872F62
`--*C. hamula Hicks 1872F62
Anzalia Termier & Termier 1947H75
`--*A. cerebriformis Termier & Termier 1947H75
Bovicornellum Howell 1934H62
`--*B. vermontense Howell 1934H62
Cestites Caster & Brooks 1956H75
`--*C. mirabilis Caster & Brooks 1956H75
Coelenteratella Korde 1959 [=Coelenterella (l. c.)]H75
`--*C. antiqua Korde 1959H75
Lenaella Korde 1959H75
`--*L. reticulata Korde 1959H75
Paramedusium Gürich 1930H62
`--*P. africanum Gürich 1930H62
Escumasia Nitecki & Solem 1973H75
`--*E. roryi Nitecki & Solem 1973H75
Tyrkanispongia Vologdin & Drozdova 1970G79
`--*T. tenua Vologdin & Drozdova 1970G79
Redkinia Sokolov 1976G79
`--*R. spinosa Sokolov 1976G79
SuvorovellidaeG79
|--Suvorovella Vologdin & Maslov 1960G79
| `--*S. aldanica Vologdin & Maslov 1960G79
`--Majella Vologdin & Maslov 1960G79
`--*M. verkhojanica Vologdin & Maslov 1960G79
Petalostroma Pflug 1973G79
`--*P. kuibis Pflug 1973G79
CupithecidaeWS93
|--Cupitheca Duan in Xing et al. 1984MP10
| `--C. manicae Duan 1983WS93
`--Actinotheca Xiao & Zhou 1984 non Cookson & Eisenack 1960 (ICBN)WS93, L95
|--*A. mirus He in Qian 1977L95
|--A. costellata Xiao & Zhou 1984WS93
`--A. dolioformis Xiao & Zhou 1984WS93
Acidocharacus Qin & Ding 1988MP10
Caveacus Landing 1995L95
`--*C. rectus Landing 1995L95
Leiperia gracileB88
Potamotrygonocotyle amazonensisB88
Ellisell Peel & Berg-Madsen 1988YK03
Arbusculites Murray 1831M65
FedomiaBJ17
CoronacollinaBJ17
Arumberia Glaessner & Wade 1975G79
`--*A. banksi Glaessner & Wade 1975G79
Gangtoucunia aspera Luo & Hu 1999SHB15
Scolethricella minorZS10
Microcalanus pygmaeusZS10
Pentagonistipes petaloidesMB12
Hagionella cultrataL04
Liangshanella rotundataL04
Dabashanella hemicyclicaL04
Pseudovendia charnwoodensisW96, EL11
Mialsemia semichatoviW96, EL11
Bonata [Bonatiidae]NS93
`--B. septata Fedonkin 1980NS93
Staurinidia crucicula Fedonkin 1985NS93
Cambromedusa furcula Willoughby & Robison 1979NS93
Brooksellidae [Protomedusae]NS93
|--Brooksella Walcott 1896NS93, H75 [incl. Laotira Walcott 1896H75]
| |--B. canyonensis Bassler 1941NS93, H75 [=Asterosoma canyonensisH75]
| `--B. silurica (von Huene 1904)NS93
`--Duodecimedusina King in Harrington & Moore 1955NS93, H75
|--*D. typica King in Harrington & Moore 1955H75
`--D. aegyptiaca Avnimelech 1966NS93
Paiutitubulitidae [Paiutiida]WS93
|--Cambrotubulites trisepta Tynan 1983WS93
`--PaiutitubulitesWS93
|--P. durhami Tynan 1983WS93
`--P. variabilis Tynan 1983WS93
Ancienta [Ancientidae]WS93
|--A. arborea Schallreuter 1981WS93
|--A. fortensis Ross 1967WS93
|--A. ohioensis Ross 1967WS93
|--A. pomerania Schallreuter 1981WS93
`--A. rossi Schallreuter 1981WS93
Konyrum [Konyriidae]WS93
`--K. varium Nazarov & Popov 1976WS93
ParacarinachitidaeWS93
|--Paracarinachites sinensis Qian & Jiang 1982 [incl. Luyanhaochiton spinus Yu 1984]WS93
`--Yangtzechiton elongatus Yu 1984WS93
Stoibostrombidus [Stoibostrombidae]WS93
`--S. crenulatus Conway Morris & Bengtson 1990WS93
Typhloesus [Typhloesidae]WS93
`--T. wellsi (Melton & Scott 1973)WS93
Lenargyrion [Utaphosphidae]WS93
`--L. knappologicum Bengtson 1977WS93
Cowiella reticulata Hinz 1987WS93
Cyrtochites pinnoides Qian 1983WS93
Deuteronectanebos papillorum Schram 1979WS93
Etacystis communis Nitecki & Schram 1976WS93
Portalia mira Walcott 1918WS93
Pyrgites mirabilis Yu 1984WS93
Stefania longula Grigor’eva 1982WS93
Tummulduria incompertya Missarzhevsky 1969WS93
Westgardia gigantea Rowland & Carlson 1983WS93
Nabaviella Mostler & Mosleh-Yazdi 1976CA06
Holoplicatella Clausen & Álvaro 2006CA06
`--*H. margarita Clausen & Álvaro 2006CA06
Wushichites minutus Qian & Xiao 1984 [incl. W. polyedrus Qian & Xiao 1984]CA06
Tumulduria Missarzhevsky 1969D78
Bronicella Sokolov 1973D78
`--B. podolicaEL11
Scheia tuberosaG31
Palaeoaplisina laminaeformisG31
Macrodus tenuistriatusG31
Zenobiella incarnataJ63
Odontoceras Serville 1833EH19
Aulozoon soliorumR22
Keretsa brutoniR22
Valdainia plumosaEL11
Ventogyrus chistyakovi Ivantsov & Grazhdankin 1997G14
Onegia Sokolov 1976G14, G79
`--O. nenoxa (Keller in Keller et al. 1974)G14
Lobularia palmataR26
Traegaardhia distosolenidiaCK10
Nephelis octoculataW17

Metazoa [Agnotozoa, Animalia, Diploblastica, Enterozoa, Epitheliozoa, Gelatinosa, Lithophyta, Parahoxozoa, Paratrilobita, Parazoa, Petalonamae, Petalonamidae, Phytozoa, Proarticulata, Spongiaria, Vendiamorpha, Vendobionta, Vendozoa, Xenoconchia]BJ17

*Pararenicola huaiyuanensis Wang 1982 [incl. Paleorhynchus anhuiensis Wang 1982, Ruedemannella minuta Wang 1982, Paleolina tortuosa Wang 1982]SWZ86

*Type species of generic name indicated

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