Eumetazoa

Reconstruction of Dinomischus, copyright Laurent B.

Belongs within: Metazoa.
Contains: Coelenterata, Dickinsoniomorpha, Xenacoelomorpha, Deuterostomia, Ecdysozoa, Rhombozoa, Gastrotricha, Gnathifera, Platyhelminthes, Nemertea, Mollusca, Sipuncula, Annelida, Bryozoa, Brachiozoa, Entoprocta.

The Eumetazoa are the basal clade of animals in the body is organised into tissues forming germ layers, including muscles and neurons. The clade unites Coelenterata and Bilateria. Bilateria are characterised by the possession of a bilaterally symmetrical body plan, together with a mesodermal germ layer giving rise to circular and longitudinal muscles (Cannon et al. 2016). Recent phylogenetic analyses of the Bilateria have mostly agreed that the Xenacoelomorpha, marine worms lacking a through-gut or protonephridia, represent the sister taxon of the majority of Bilateria in the Nephrozoa. The through-gut and discrete excretory organs evolved in the Nephrozoa (Cannon et al. 2016).

Most recent analyses have supported division of the Nephrozoa between the clades Deuterostomia and Protostomia. As the through gut develops in the embryo, the original blastopore in the gastrula becomes the mouth in protostomes but the anus in deuterostomes (Runnegar 2022). The protostomes in turn are divided between the Ecdysozoa and Spiralia, with the latter being a clade identified by molecular analysis whose members typically exhibit spiral cell cleavage in the early embryo. The Spiralia have alternatively been named the Lophotrochozoa, in reference to the clade associating animals bearing a lophophore (bryozoans and brachiozoans) and those with a trochophore-like ciliated larva (annelids and molluscs).

The trouble with coelosclerites
Published 23 September 2010

A couple of years ago, I posted a brief review of the chancelloriids, mysterious sessile animals from the Cambrian period. As explained in that post (which I’d recommend reading before this one), chancelloriids are remarkable for how much we know about them while still being unable to place them anywhere in the animal family tree. However, there are two main options that are currently supported: one is that chancelloriids are sponge-grade animals, probably in the stem-group of modern Epitheliozoa (the clade including coelenterates and bilaterians, which differ from sponges in having a differentiated external skin around their bodies); the other is that chancelloriids are related to other Cambrian animals such as halkieriids, which have themselves been shown to be closely related to molluscs (Vinther & Nielsen 2005).

Diagram of coelosclerite microstructure from Porter (2008).

The sponge interpretation of chancelloriids has some strong points marshalling in its favour: chancelloriids lack any sign of bilateral symmetry and no sign has been recognised in them of differentiated organ systems. The main feature associating them with halkieriids is the microstructure of their sclerites. Chancelloriids and halkieriids (and a couple of other Cambrian families) possessed sclerites with a microstructure unknown for any other animal group. Known as coelosclerites, these structures were hollow and would have been secreted as a single unit without any subsequent growth. The greater part of the sclerite was formed of aragonite fibres, arranged parallel to the axis of the sclerite. External protrusions on the sclerite were formed by aragonite bundles sitting at an angle to the main body. A thin layer, probably originally organic, covered the outer surface of the sclerite (Porter 2008).

Porter (2008) felt that the similarity between chancelloriid and halkieriid sclerites was so great that it was unlikely that they had evolved independently. The coelosclerite was far from being the only way to develop such a structure: the Cambrian and subsequent periods have seen the evolution of many other sclerite-possessing animals, all of which exhibited different sclerite microstructures. Nor could any convergence be explained by selective pressures: the sessile chancelloriids and slug- or chiton-like halkieriids would have ecologically very different animals. If the coelosclerite structure arose independently in the two groups, the similarities would have to be accepted as pure coincidence.

However, if we accept that coelosclerites had a single origin, we have to explain the complete absence of apparent bilaterian traits in chancelloriids. Many groups of bilaterians have lost their ancestral bilateral symmetry: tunicates, entoprocts, echinoderms, for instance. None of them, however, have lost all trace of their ancestry to quite the same degree that chancelloriids would have had to. Porter (2008) proposed two options: (1) chancelloriids were indeed highly derived bilaterians forming a clade with halkieriids, or (2) chancelloriids were sponge-grade stem-epitheliozoans; coelosclerites arose in the common ancestor of chancelloriids and bilaterians but were subsequently lost by bilaterians other than halkieriids.

Option 2 might appear tempting if halkieriids were close to the base of bilaterians, but it is well-established that they are not. If halkieriids are interpreted as stem-trochozoans (a fairly conservative interpretation) then coelosclerites would have had to have been lost at least six times, in the ancestors of ctenophores, cnidarians, deuterostomes, ecdysozoans, bryozoans and platyzoans (and that is ignoring more phylogenetically contentious groups such as acoelomorphs and chaetognaths that could potentially increase the number even further). If, as seems more likely, halkieriids are stem-molluscs, we have to factor in another two losses for brachiozoans and annelids (and, again, I’m ignoring phylogenetic renegades such as entoprocts). And in the case of brachiozoans, the greater part of the brachiozoan stem group appear to have themselves possessed sclerites; Porter’s hypothesis 2 would require the stem-brachiozoans to have lost coelosclerites, only to re-evolve a distinct new sclerite form shortly afterwards.

So, in my opinion, the only really viable options are coelosclerites evolved convergently in two entirely separate lineages, or coelosclerite-possessing animals formed a single monophyletic clade. My personal inclination would be to favour the latter; the examples of ascidians and others demonstrate that significant re-organisations of the bilaterian body plan are not a priori impossible. Of course, the supporting evidence either way remains shaky, and the whole structure could still come tumbling down tomorrow.

Arthropods in the Precambrian?
Published 12 May 2014
The Ediacaran animal Spriggina floundersi, from here.

The Ediacaran biota has been touted as one of the great mysteries of palaeontology. Comprising the latest part of the Precambrian era, the Ediacaran is generally believed to have given us the earliest known animal fossils. However, palaeontologists have disagreed on just how the Ediacaran fossils relate to modern animals (see McCall 2006 for an exhaustively detailed review). Some see the Ediacarans as including the ancestors of groups that remain with us today: jellyfish, corals, comb jellies, sponges. Others see Ediacarans as outside the modern lineages: ancient animal groups that were swept aside by more modern animals at the beginning of the Cambrian. And some have even questioned whether the Ediacarans were even animals at all, suggesting links instead to fungi or Foraminifera, or even that they were an entirely independent lineage unrelated to any modern multicellular organisms.

In 1996, Benjamin Waggoner proposed the name ‘Cephalata’ for a clade uniting the arthropods with two groups of Ediacaran organisms: the Sprigginidae and the Vendiamorpha. These are among the most undeniably animal-like of the Ediacarans. The sprigginids (including Spriggina shown at the top of the post) have an undivided ‘head’ followed by a long segmented body. The vendiamorphs are shield-like organisms that also show evidence for segment-like divisions behind the ‘head’, such as branching internal structures that may represent side-branches of an internal gut.

The vendiamorph Vendia sokolovi, from Ivantsov (2004).

It is difficult to see these taxa as anything other than mobile animals. One supporter of non-animalian affinities for the Ediacarans, Adolf Seilacher, did suggest that Spriggina was a sessile organism, maintaining that the ‘head’ was in fact a holdfast while the ‘body’ extended upwards like the frond of a sea pen (I have seen a memorable reconstruction, though unfortunately I can’t recall where, showing an individual of mobile Spriggina crawling past a cluster of sessile Spriggina). However, the numerous Spriggina specimens that have been found in Australia and Russia are invariably preserved lying flat, while sessile organisms from the same locations are preserved with the holdfast below the level of the body. Vendiamorphs, on the other hand, are simply not shaped in a way that allows them to be seen as anything other than lying flat. An immobile sprigginid or vendiamorph lying flat below the water would have been vulnerable to being buried by sediment, without any way of digging itself back out.

But if sprigginids and vendiamorphs were definitely animals, what kind of animals were they? It is at this point that things get a bit more vague. Their segmented appearance immediately suggests arthropods (and onychophorans) or annelids, but there is not a great deal to suggest one or the other. The differentiated head of sprigginids suggests the head of an arthropod, while vendiamorphs have been compared to the larvae of arthropods such as trilobites. However, it is unclear whether the Ediacaran taxa possessed anything like the limbs of arthropods and related taxa. The segments of sprigginids may be separated at the edges, and some have argued that folds in vendiamorph fossils are suggestive of limbs underneath a dorsal shield, but there is nothing that one would call unequivocal. Lateral outgrowths of sprigginids may correlate to annelid parapodia instead of arthropod limbs, and folds in the bodies of vendiamorphs may be nothing more than that. We recognise relationships between fossil and extant animals on the basis of whether they have features in common, but our assessment of what features they have may be coloured by what features we expect to see.

Another possible vendiamorph, Parvancorina minchami, from here. Note the fine parallel lines on the body, which some have interpreted as the outlines of limbs.

Some authors have drawn attention to a feature of both vendiamorphs and sprigginids that is visible in the image of Vendia above: their so-called ‘glide reflectional symmetry’. Though their bodies appear segmented, the segments do not go straight across the body as one might expect. Instead, the left and right sides of the body are slightly offset from each other. For this reason, some authors have claimed that these animals do not show true bilateral symmetry and hence argued for placing them outside the Bilateria crown group, along its stem. However, others have suggested that the offset between sides may be an artefact of preservation. Even if it was indeed a feature of the living animal, glide reflectional symmetry may not necessarily force the sprigginids outside the Bilateria: a number of living bilaterians also show a certain degree of symmetry offset either as adults or during development, including basal chordates (Waggoner 1996).

During the period of the Cambrian, directly after the Ediacaran, we have access to beautifully preserved fossil deposits that have allowed us to characterise many animals from that period in exquisite detail. No such fossils exist for the Ediacaran; instead, Ediacaran animals are mostly preserved in coarse sediments that preserve only relatively broad features of the fauna. This can turn the Ediacarans into tantalising shadows, and what we see in them can say more about our assumptions than the animals themselves.

Linnaeus’ infernal fury?
Published 5 March 2017

The starting point of modern zoological nomenclature (Clerck notwithstanding) has been established as the tenth edition of Linnaeus’ Systema Naturae, published in 1758. Linnaeus divided the animal kingdom between six classes, with vertebrates making up four (Mammalia, Aves, Amphibia and Pisces) and invertebrates assigned to just two. One of these, Insecta, essentially corresponded to modern arthropods, and all other invertebrates were included in the class Vermes, ‘worms’. Linnaeus’ concept and arrangement of Vermes bears little resemblance to anything that exists in modern zoological classifications; with the study of invertebrate anatomy still in its absolute infancy, he was largely classifying animals based on their overall external appearance alone. One of Linnaeus’ orders of Vermes, the ‘Intestina’, defined as ‘simple, shell-less and limb-less’, included animals now classified as annelids, nematodes, molluscs and even a chordate (the hagfish Myxine glutinosa). It also included a species whose identity would be debated for the next several decades: the ‘infernal fury’, Furia infernalis.

A reconstruction of Furia infernalis, from Piter Kehoma Boll.

Furia infernalis was described by Linnaeus as “Corpus filiforme, continuum, aequale, utrinque ciliatum: aculeis reflexis corpori appressis” (‘body thread-like, continuous, uniform, ciliated on both sides with reflexed spinules appressed to the body’). It was found in marshes of southern Sweden and Finland. Linnaeus went on to record that F. infernalis was, “Pessima omnium, ex aethere decidua in corpora animalium, ea momento citius penetrat, intra horae quadrantem dolore atrocissimo occidit“: the ‘worst of all, falling from the sky onto the bodies of animals, into which it rapidly penetrates within a moment, striking [the victim] down with the most atrocious pain within quarter of an hour’. Linnaeus had good reason to highlight this animal’s unpleasantness: he had been attacked by one himself when collecting botanical specimens in 1728, and barely escaped the resulting ailment with his life. A more detailed description of “der Höllenwurm” was compiled by Jördens (1802): it was a very slender worm, about the length of a nail, of a pale yellow or fleshy colour (other authors described it as greyish), with one end black. It climbed up standing vegetation, from whence it was carried by the breeze onto the exposed skin of humans and animals into which it rapidly burrowed. For victims, the first sign of its presence was usually a sudden pain in the afflicted spot, like the stab of a needle, and a small black spot marking the worm’s entry point. A violent itching followed that developed into severe and extensive inflammation, often accompanied by fever; in the majority of cases, the affliction was so violent that the victim was dead within a matter of days if immediate action was not taken. If applied quickly enough, the worm could sometimes be drawn out with a poultice of fresh cheese curds. Otherwise, treatment required the careful dissection of the worms from between the muscle tissue into which they had entered, a process that (considering the surgical facilities available at the time) must have nearly as hazardous as the original infection.

As can be imagined, the attacks of this animal were greatly feared. In 1823–1824, an epidemic of Furia attacks spread through herds of livestock in Swedish and Finnish Lapland; thousands of head of reindeer perished, as well as countless cattle and sheep. Scavengers such as wolves feeding on the carcasses themselves sickened and died. One account from the time involves a young woman who was shearing wool from a recently deceased sheep (on a waste not, want not principle, I suppose) when she felt the tell-tale sting on a knuckle. Her life was saved by her master who was working nearby, when he quickly chopped off the affected finger with an axe. So great was the devastation that Norway, which had hitherto been free of the worm, passed an edict banning the import of animal furs from affected areas (Brooke 1827).

There were some, however, who greeted the description of Furia infernalis with skepticism. The idea of a tiny worm that somehow flew through the air and caused almost instantaneous mortality seemed fantastic. Even more problematic was the dearth of specimens. Many had seen the wounds caused by the worm and observed its effects; very few had seen the worm itself. Linnaeus himself had only seen a single, very poorly preserved specimen submitted to him by a church pastor. Most of the details about the worm’s supposed appearance came from a single source, an article written by Solander, a student of Linnaeus’. The Academy of Sciences at Stockholm, naturally keen to discover all they could about such a scourge afflicting their country, offered generous rewards to anyone who could procure them a genuine specimen; no such specimen was forthcoming. Eventually, a consensus was reached: the worm Furia infernalis was an entirely fabulous animal, with no place in the annals of physical zoology. By 1827, notwithstanding the epidemic of only a few years previously, Brooke was able to comment that one could quite easily accept that something had affected the supposed victims of Furia without presuming that that something had to be the Furia itself. Even Linnaeus eventually came to accept that his inclusion of Furia in the Systema Naturae had been an error.

That Furia infernalis never existed outside the realms of fantasy remains the accepted wisdom to this day. But in that case, what did afflict Linnaeus and other unfortunates wandering the marshes of Sweden in the early 1700s? One thing that struck me was how much I was reminded of the more recent phenomenon here in Australia of ‘white-tailed spider bites’. In recent decades, many people (including many medical professionals) have attributed serious ulcerative skin lesions, sometimes so serious that treatments such as skin grafts are required, to the bite of white-tailed spiders Lampona spp., common ground-running spiders often encountered near human dwellings. The actual evidence linking white-tailed spiders to such injuries is minimal; indeed, a clinical survey of 130 confirmed white-tail bites by Isbister & Gray (2003) found not a single incidence of one leading to ulceration. In both the ‘Furia attacks’ and the ‘white-tailed spider bites’, it seems likely that the primary culprit is bacterial infections resulting from opportunistic pathogens such as Streptococcus and Staphylococcus species. The initial wound may indeed have been caused by something like an animal bite or sting, or for that matter a splinter or pin-prick. Germ theory would not become widely accepted until the mid- to late 1800s; when Linnaeus compiled the Systema Naturae, flying worms probably seemed as good an explanation as any. The first ‘attack’ recorded by Furia victims may have simply been the first moment they noticed the infection’s symptoms. And the ‘worms’ dissected out of advanced victims? Personally, I’m inclined to suspect that they may have been small pieces of tissue from the unfortunate sufferers themselves.

The exact causes of the 1823 epidemic are probably lost to history. Brooke (1827) stated that faculty at the Stockholm academy “had been led to consider the disorder by which [the reindeer] were attacked as a particular variety of hydrophobia“. He also mentioned another possibility: reindeer were known to be vulnerable to inflammation of the brain, and dissections of the brains of deer killed by this condition sometimes revealed the presence of “a small vesicular worm“. We can now recognise these vesicles as the cysts of hydatid tapeworms, which can hatch to cause tapeworm infections in any predator that eats the flesh of their host. So perhaps the 1823 epidemic was caused by a worm after all—just not the worm that was blamed.

Seriously, what is this thing?
Published 26 June 2019
Spinita spp., from Kordè in Koren’ (2003). 1: S. sanashticgolica, 2: S. cryptosa, 3: S. spinoglobosa.

The figure above comes from a Russian book, Атлас ископаемой фауны и флоры палеозоя Республики Бурятия (‘Atlas of the Palaeozoic fossil fauna and flora of the Republic of Buryatia’), edited by T. N. Koren’ and published in 2003 in Ulan-Udè. Buryatia is a Russian republic in south-eastern Siberia, wrapping around the eastern and southern coasts of Lake Baikal. The fossils shown above come from the Lower Cambrian (the Botomian stage in the Russian system) of the Eastern Sayan Mountains. Going by the appearance of the figures, I presume they’re being examined as thin sections, a commonly used method for studying Palaeozoic microfossils. Though as microfossils go, these are definitely on the large side: the specimen figured as 1a is a centimetre long and three millimetres wide. The other specimens are smaller, about half a centimetre in length.

When I saw these figures, I was just mystified. Their describer, K. B. Kordè, regarded them as a new class of ‘Nemathelminthes’, claiming that ‘the first impression that is created from the described material is that they are representatives of the Kinorhyncha or Gastrotricha’. I’m not sure that I would agree with that. I found myself wondering if they were even animals, though I was hard pressed to think what else they might be. Not being familiar with the interpretation of thin sections, the thought did cross my mind to ask how certain can we be that these are even fossils, but I think that may be a bit uncharitable. Kordè also suggested that a break in the apparent cuticle of the S. sanashticgolica specimen about halfway along the flattened side (interpreted as the venter) might be the mouth. If so, that would be very unlike any kinorhynch or gastrotrich I’ve heard of. Could be a flatworm, I suppose, though Kordè then goes on to read the cluster of spines at one end (as magnified in figure 2b) as marking the anus which would seem to put paid to that! Said spines, or papillae, or whatever, are also supposed to have medial channels that Kordè interprets as nephridia.

All in all, I can’t express anything other than confusion about this one. Certainly I haven’t been able to find any further commentary on these enigmas; a Google search for Spinita sanashticgolica brings up just one result, an offhand mention in this book which seems to be just referring to it as found in the same formation as another fossil. Confusingly enough, that mention seems to date from 1986, a good seventeen years before Koren’ (2003) was even printed: whether that indicates that the latter publication was not actually the first time the description of Spinita saw print, or whether this genus saw time floating around in unpublished communications, I have no idea.

Systematics of Eumetazoa
<==Eumetazoa [Coeloscleritophora, Polypi, Radiaria, Tubulariae]
|--+--CoelenterataOH17
| `--Kimberella Wade 1972R22, G79 (see below for synonymy)
| `--*K. quadrata (Glaessner & Wade 1966) [=*Kimberia quadrata]G79
`--+--DickinsoniomorphaR22
|--BilaterialomorphaBJ17
| |--Paravendia janaeEL11
| |--Temnoxa molliuscula Ivantsov in Ivantsov et al. 2004G14
| |--Solza margarita Ivantsov in Ivantsov et al. 2004G14
| |--Brachina Wade 1972G14, G79
| | `--*B. delicata Wade 1972G79
| `--Parvancorina Glaessner 1958W96, R22 [Parvancorinidae]
| |--*P. minchami Glaessner in Glaessner & Daily 1959G79
| `--P. saggita Ivantsov in Ivantsov et al. 2004G14
`--Bilateria [Acoelomata, Coelomata, Enterocoela, Heteraxonia, Intestina, Metahelminthes, Triploblastica]OH17
| i. s.: Enchostoma Miller & Gurley 1896F62
| `--‘Hyolithes’ milleri Sinclair 1946 (see below for synonymy)F62
| Haileyia Ruedemann 1934H62
| `--*H. adhaerens Ruedemann 1934H62
| Hesionites Fritsch 1907H62
| `--*H. bioculata Fritsch 1907H62
| Hirudopsis Moberg & Segerberg 1906H62
| `--*H. koepingensis Moberg & Segerberg 1906H62
| Klakesia Ruedemann 1934H62
| `--*K. simplex Ruedemann 1934H62
| Propolynoe Fritsch 1907H62
| `--*P. laccoei Fritsch 1907H62
| Redoubtia Walcott 1918H62
| `--*R. polypodia Walcott 1918H62
| Sarcionata Costa 1856H62
| `--*S. proboscidata Costa 1856H62
| Tosalorbis Katto 1960H62
| `--*T. hanzawai Katto 1960H62
| Balanophorus Briganti 1825L09
| Anticalyptraea Quinstedt 1867 [incl. Autodetus Lindström 1884]KC60
| Furia Linnaeus 1758L58
| `--*F. infernalis Linnaeus 1758L58
|--XenacoelomorphaCV16
`--Nephrozoa [Eubilateria, Eutriploblastica, Gasteromelea, Sympoda]HO09
| i. s.: Amimomus de Montfort 1808 (n. d.)T64
| `--*A. elephantinus de Montfort 1808 (n. d.)T64
| Vernanimalcula Chen, Bottjer et al. 2004CB04
| `--*V. guizhoena Chen, Bottjer et al. 2004CB04
|--DeuterostomiaHO09
`--Protostomia (see below for synonymy)HO09
|--EcdysozoaHO09
`--Spiralia (see below for synonymy)HO09
| i. s.: Cambrotentacus Zhang, Shu et al. 2001ZS01
| `--*C. sanwuia Zhang, Shu et al. 2001ZS01
| RhombozoaSRT18
|--GastrotrichaVP19
|--GnathiferaVP19
`--Platytrochozoa (see below for synonymy)VP19
| i. s.: Lobatocerebrum [Lobatocerebridae, Lobatocerebromorpha]H96
| `--L. psammicola Rieger 1980ZHT01
|--PlatyhelminthesVP19
|--NemerteaVP19
|--+--MolluscaVP19
| `--+--SipunculaPE16
| `--+--Phragmochaeta canicularisPE16, PTV14
| `--+--Canadia Walcott 1911PE16, H62 [Canadidae, Canadiidae]
| | `--*C. spinosa Walcott 1911H62
| `--+--AnnelidaVP19
| `--Burgessochaeta [Burgessochaetidae]PE16
| `--B. setigera (Walcott 1911) [=Canadia setigera]E-J04
`--+--+--BryozoaVP19
| `--BrachiozoaVP19
`--+--EntoproctaVP19
|--Symbion [Cycliophora, Eucycliophora, Symbiida, Symbiidae]HO09
| |--S. americanusGO06
| `--S. pandora Funch & Kristensen 1995A99
`--Dinomischus [Dinomischide]C12
|--D. isolatus Conway Morris 1977WS93
`--D. venustus Chen et al. 1989WS93

Eumetazoa incertae sedis:
Ocellaria Ramond 1801R01
|--O. inclusa Ramond 1801R01
`--O. nuda Ramond 1801R01
Thambetolepis delicata Jell 1981P08
Aurisella Qian & Xiao 1984 (see below for synonymy)MP10
Chancelloriella irregularis Demidenko 2000MP10
Monospinites Sayutina in Vasil’eva & Sayutina 1988MP10
Mirusilites He & Yang 1986MP10
Archicladium Qian & Xiao 1984MP10
ZhiiginitesEL11
Hippopharangites Bengtson in Bengtson et al. 1990MP10
`--H. dailyi Bengtson in Bengtson et al. 1990P08
Cambrothyra Qian & Zhang 1983 (see below for synonymy)MP10
`--*C. ampulliformis Qian & Zhang 1983 (see below for synonymy)MP10
AustralohalkieriaP08
|--A. parva (Conway Morris in Bengtson et al. 1990)P08
`--A. superstes Porter 2004P08
Eremactis Bengtson & Conway Morris in Bengtson et al. 1990MP10
|--E. conara Bengtson & Conway Morris in Bengtson et al. 1990MP10
`--E. mawsoni Bengtson & Conway Morris in Bengtson et al. 1990MP10
Pharetria socialisG20
‘Coronella’ Goldfuss 1820 non Laurenti 1768G20
`--*C. fimbriataG20
Pedicellaria tridensG20

Pseudofossils: Cambrothyra miliaria Duan & Cao 1989MP10
Situlitesta antiquata Duan & Cao 1989MP10
Situlitesta cyclocarpa Duan & Cao 1989MP10

Aurisella Qian & Xiao 1984 [incl. Ninella Missarzhevsky in Missarzhevsky & Mambetov 1981 nec Gray 1850 nec Malakhova 1975]MP10

Cambrothyra Qian & Zhang 1983 [incl. Acatomus Duan 1986, Clinopa Duan 1986, Cyphinites Duan, Cao & Zhang 1993, Globifructus Geng & Zhang 1987, Horridomus Duan 1986, Hubeitesta Duan 1986, Lapistamnia Duan, Cao & Zhang 1993, Laxicavia Duan, Cao & Zhang 1993, Mirabichitina Yang, He & Deng 1983 (n. n.), Mirabifolliculus Yang & He 1984, Nanjiangochitina Yang, He & Deng 1983 (n. n.), Nanjiangofolliculus Yang & He 1984, Ovitesta Duan 1986, Parahorridomus Duan, Cao & Zhang 1993, Pollofructus Geng & Zhang 1987, Situlitesta Duan 1986, Trymitesta Duan 1986, Turbinella Duan, Cao & Zhang 1993 non Lamarck 1799, Tympanites Duan, Cao & Zhang 1993]MP10

*Cambrothyra ampulliformis Qian & Zhang 1983 [=Cambrotyca (l. c.) ampulliformis; incl. Situlitesta afflata Duan 1986, Hubeitesta amblybasis Duan 1986, Situlitesta baccata Duan 1986, Parahorridomus biarmillaris Duan, Cao & Zhang 1993, Acatomus bursoides Duan 1986, Anterosculum cambricum Duan, Cao & Zhang 1993, Situlitesta cordata Duan 1986, Laxicavia crassa Duan, Cao & Zhang 1993, Cambrothyra cymatoidea Duan 1986, Lax. debilis Duan, Cao & Zhang 1993, Trymitesta declinata Duan 1986, Tr. ellipsoidalis Duan 1986, Clinopa gibberosa Duan 1986, Cambrothyra glandiformis Duan 1986, Trymitesta globularis Zhang in Zhao et al. 1988, Ca. granosa Geng & Zhang 1987, Acatomus lacrimiformis Duan 1986, Tympanites lebericus Duan, Cao & Zhang 1993, Globifructus meloniformis Geng & Zhang 1987, Cyphinites nidificus Duan, Cao & Zhang 1993, Pollofructus nodus Geng & Zhang 1987, Clinopa nucleola Duan 1986, Cyphinites ovalis Duan, Cao & Zhang 1993, Situlitesta rostellata Duan 1986, Globifructus scutatus Geng & Zhang 1987, Lapistamnia septalis Duan, Cao & Zhang 1993, Horridomus stephanoideus Duan 1986, Turbinella trochalis Duan, Cao & Zhang 1993, Ovitesta truncata Duan 1986, Cambrothyra truncata, Ca. vasiformis Duan 1986, H. vemetovatus Duan 1986, Clinopa verruculata Duan 1986, Cl. xihaopingensis Duan 1986]MP10

‘Hyolithes’ milleri Sinclair 1946 [=Hyolithes lanceolatus Miller 1892 non Theca lanceolatus Morris 1845, *Enchostoma lanceolatum]F62

Kimberella Wade 1972R22, G79 [=Kimberia Glaessner & Wade 1966 non Cotton & Woods 1935G79; Kimberellidae, Kimberellomorpha]

Platytrochozoa [Agama, Canadiacea, Coelhelminthes, Conchozoa, Dorsalia, Eutrochozoa, Halkierida, Kryptrochozoa, Neotrochozoa, Serpulae, Torimorphidae, Trochozoa, Vermizoa]VP19

Protostomia [Annularia, Aschelminthes, Enthelmintha, Gastroneuralia, Gephyrea, Gymnodermata, Miskoida, Miskoiida, Paracoelomata, Pleuropteria, Proterostoma, Pseudocoelomata, Pulvinifera, Schizocoela]HO09

Spiralia [Acanthognatha, Lacunifera, Lophozoa, Lophophorata, Lophotrochozoa, Mesozoa, Molluscoidea, Moruloidea, Neotrichozoa, Monokonta, Parenchymia, Plathelminthomorpha, Platyzoa, Procoelomata, Prosomastigozoa]HO09

*Type species of generic name indicated

References

[A99] Ax, P. 1999. Das System der Metazoa II. Ein Lehrbuch der phylogenetischen Systematik. Gustav Fisher Verlag: Stuttgart (translated: 2000. Multicellular Animals: The phylogenetic system of the Metazoa vol. 2. Springer).

Brooke, A. de C. 1827. A Winter in Lapland and Sweden, with various observations relating to Finmark and its inhabitants; made during a residence at Hammerfest, near the North Cape. John Murray: London.

[BJ17] Budd, G. E., & S. Jensen. 2017. The origin of the animals and a ‘savannah’ hypothesis for early bilaterian evolution. Biological Reviews 92 (1): 446–473.

[CV16] Cannon, J. T., B. C. Vellutini, J. Smith, III, F. Ronquist, U. Jondelius & A. Hejnol. 2016. Xenacoelomorpha is the sister group to Nephrozoa. Nature 530: 89–93.

[C12] Chen, J.-Y. 2012. Evolutionary scenario of the early history of the animal kingdom: evidence from Precambrian (Ediacaran) Weng’an and Early Cambrian Maotianshan biotas, China. In: Talent, J. A. (ed.) Earth and Life: Global biodiversity, extinction intervals and biogeographic perturbations through time pp. 239–379. Springer.

[CB04] Chen, J.-Y., D. J. Bottjer, P. Oliveri, S. Q. Dornbos, F. Gao, S. Ruffins, H. Chi, C.-W. Li & E. H. Davidson. 2004. Small bilaterian fossils from 40 to 55 million years before the Cambrian. Science 305: 218–222.

[E-J04] Eibye-Jacobsen, D. 2004. A reevaluation of Wiwaxia and the polychaetes of the Burgess Shale. Lethaia 37: 317–335.

[EL11] Erwin, D. H., M. Laflamme, S. M. Tweedt, E. A. Sperling, D. Pisani & K. J. Peterson. 2011. The Cambrian conundrum: early divergence and later ecological success in the early history of animals. Science 334: 1091–1097.

[F62] Fisher, D. W. 1962. Small conoidal shells of uncertain affinities. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt W. Miscellanea: Conodonts, Conoidal Shells of Uncertain Affinities, Worms, Trace Fossils and Problematica pp. W98–W143. Geological Society of America, and University of Kansas Press.

[GO06] Giribet, G., A. Okusu, A. R. Lindgren, S. W. Huff, M. Schrödl & M. K. Nishiguchi. 2006. Evidence for a clade composed of molluscs with serially repeated structures: monoplacophorans are related to chitons. Proceedings of the National Academy of Sciences of the USA 103 (20): 7723–7728.

[G79] Glaessner, M. F. 1979. Precambrian. In: Robison, R. A., & C. Teichert (eds) Treatise on Invertebrate Paleontology pt A. Introduction. Fossilisation (Taphonomy), Biogeography and Biostratigraphy pp. A79–A118. The Geological Society of America, Inc.: Boulder (Colorado), and The University of Kansas: Lawrence (Kansas).

[G20] Goldfuss, G. A. 1820. Handbuch der Naturgeschichte vol. 3. Handbuch der Zoologie pt 1. Johann Leonhard Schrag: Nürnberg.

[G14] Grazhdankin, D. 2014. Patterns of evolution of the Ediacaran soft-bodied biota. Journal of Paleontology 88 (2): 269–283.

[H96] Haszprunar, G. 1996. The Mollusca: coelomate turbellarians or mesenchymate annelids? In: Taylor, J. D. (ed.) Origin and Evolutionary Radiation of the Mollusca pp. 1–28. Oxford University Press: Oxford.

[HO09] Hejnol, A., M. Obst, A. Stamatakis, M. Ott, G. W. Rouse, G. D. Edgecombe, P. Martinez, J. Baguña, X. Bailly, U. Jondelius, M. Wiens, W. E. G. Müller, E. Seaver, W. C. Wheeler, M. Q. Martindale, G. Giribet & C. W. Dunn. 2009. Assessing the root of bilaterian animals with scalable phylogenomic methods. Proceedings of the Royal Society of London Series B—Biological Sciences 276 (1677): 4261–4270.

[H62] Howell, B. F. 1962. Worms. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt W. Miscellanea: Conodonts, Conoidal Shells of Uncertain Affinities, Worms, Trace Fossils and Problematica pp. W144–W177. Geological Society of America, and University of Kansas Press.

Isbister, G. K., & M. R. Gray. 2003. White-tail spider bite: a prospective study of 130 definite bites by Lampona species. Medical Journal of Australia 179: 199–202.

Ivantsov, A. Yu. 2004. New Proarticulata from the Vendian of the Arkhangel’sk region. Paleontologicheskii Zhurnal 2004 (3): 21–26 (translated: Paleontological Journal 38 (3): 247–253).

Jördens, J. H. 1802. Entomologie und Helminthologie des Menschlichen Körpers, oder Beschreibung und Abbildung der Bewohner und Feinde desselben unter den Insekten und Würmern vol. 2. Gottfried Adolph Grau: Hof.

[KC60] Knight, J. B., L. R. Cox, A. M. Keen, R. L. Batten, E. L. Yochelson & R. Robertson. 1960. Gastropoda: systematic descriptions. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt I. Mollusca 1: Mollusca—General Features, Scaphopoda, Amphineura, Monoplacophora, Gastropoda—General Features, Archaeogastropoda and some (mainly Paleozoic) Caenogastropoda and Opisthobranchia pp. I169–I331. Geological Society of America, and University of Kansas Press.

[L09] Lea, A. M. 1909. Revision of the Australian and Tasmanian Malacodermidae. Trans. Ent. Soc. Lond. 1909 (1): 45–251, pls 2–6.

[L58] Linnaeus, C. 1758. Systema Naturae per Regna Tria Naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata. Laurentii Salvii: Holmiae.

McCall, G. J. H. 2006. The Vendian (Ediacaran) in the geological record: enigmas in geology’s prelude to the Cambrian explosion. Earth-Science Reviews 77: 1–229.

[MP10] Moore, J. L., S. M. Porter, M. Steiner & G. Li. 2010. Cambrothyra ampulliformis, an unusual coeloscleritophoran from the Lower Cambrian of Shaanxi Province, China. Journal of Paleontology 84 (6): 1040–1060.

[OH17] Ou, Q., J. Han, Z. Zhang, D. Shu, G. Sun & G. Mayer. 2017. Three Cambrian fossils assembled into an extinct body plan of cnidarian affinity. Proceedings of the National Academy of Sciences of the USA 114 (33): 8835–8840.

[PE16] Parry, L. A., G. D. Edgecombe, D. Eibye-Jacobsen & J. Vinther. 2016. The impact of fossil data on annelid phylogeny inferred from discrete morphological characters. Proceedings of the Royal Society of London Series B—Biological Sciences 283: 20161378.

[P08] Porter, S. M. 2008. Skeletal microstructure indicates chancelloriids and halkieriids are closely related. Palaeontology 51 (4): 865–879.

[R01] Ramond, C. 1801. Nouveau genre de polypiers fossiles. Bulletin des Sciences, par la Societé Philomathique de Paris 2 (47): 177.

[R22] Runnegar, B. 2022. Following the logic behind biological interpretations of the Ediacaran biotas. Geological Magazine 159 (7): 1093–1117.

[SRT18] Schiffer, P. H., H. E. Robertson & M. J. Telford. 2018. Orthonectids are highly degenerate annelid worms. Current Biology 28: 1970–1974.

[T64] Teichert, C. 1964. Doubtful taxa. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt K. Mollusca 3. Cephalopoda—General Features—Endoceratoidea—Actinoceratoidea—Nautiloidea—Bactritoidea pp. K484–K490. The Geological Society of America and the University of Kansas Press.

[VP19] Vinther, J., & L. A. Parry. 2019. Bilateral jaw elements in Amiskwia sagittiformis bridge the morphological gap between gnathiferans and chaetognaths. Current Biology 29: 881–888.

[W96] Waggoner, B. M. 1996. Phylogenetic hypotheses of the relationships of arthropods to Precambrian and Cambrian problematic fossil taxa. Systematic Biology 45 (2): 190–222.

[WS93] Wills, M. A., & J. J. Sepkoski Jr. 1993. Problematica. In: Benton, M. J. (ed.) The Fossil Record 2 pp. 543–554. Chapman & Hall: London.

[ZS01] Zhang, X., D. Shu, Y. Li & J. Han. 2001. New sites of Chenjiang fossils: crucial windows on the Cambrian explosion. Journal of the Geological Society 158: 211–218.

[ZHT01] Zrzavý, J., V. Hypša & D. F. Tietz. 2001. Myzostomida are not annelids: molecular and morphological support for a clade of animals with anterior sperm flagella. Cladistics 17: 170–198.

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