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Phoronids, together with brachiopods and bryozoans, form the animal clade Lophophorata. Modern lophophorates are quite diverse—some can biomineralize while others are soft‐bodied, they could be either solitary or colonial, and they develop through various eccentric larval stages that undergo different types of metamorphoses. The diversity of this clade is further enriched by numerous extinct fossil lineages with their own distinct body plans and life histories. In this review, I discuss how data on phoronid development, genetics, and morphology can inform our understanding of lophophorate evolution. The actinotrocha larvae of phoronids is a well documented example of intercalation of the new larval body plan, which can be used to study how new life stages emerge in animals with biphasic life cycle. The genomic and embryonic data from phoronids, in concert with studies of the fossil lophophorates, allow the more precise reconstruction of the evolution of lophophorate biomineralization. Finally, the regenerative and asexual abilities of phoronids can shed new light on the evolution of coloniality in lophophorates. As evident from those examples, Phoronida occupies a central role in the discussion of the evolution of lophophorate body plans and life histories. RESEARCH HIGHLIGHTS: Phoronida is a crucial clade for the understanding of lophophorate evolution. The recent findings on their development, combined with new fossils, allow a reconstruction of how larvae, armor, and asexuality evolved in Lophophorata. [ABSTRACT FROM AUTHOR]

Cambrian Series 2 shelly fossils from thick carbonate successions in East Antarctica have received limited systematic treatment through the 20th century. Described here are the East Antarctic camenellan tommotiids from the Shackleton Limestone in the Central Transantarctic Mountains and the Schneider Hills limestone in the Argentina Range. This material comes from both newly sampled collections and incompletely described material from older collections. The assemblage supports correlation to the Dailyatia odyssei Zone and Pararaia janeae Trilobite Zone of South Australia, with the newly examined specimens of Dailyatia decobruta from the Shackleton Limestone providing direct correlation to the Mernmerna Formation of the Ikara-Flinders Ranges and White Point Conglomerate of Kangaroo Island. These East Antarctic assemblages include five species referred to Dailyatia, in addition to an undetermined kennardiid species and fragments of the problematic Shetlandia multiplicata. The results further corroborate the notion that fossiliferous carbonate clasts found on King George Island were sourced from the same carbonate shelf as the Shackleton Limestone, with the taxon S. multiplicata found in both units. The Schneider Hills limestone in the Argentina Range has yielded sclerites of Dailyatia icari sp. nov., currently only known from this location.

The lower Cambrian (Series 2) White Point Conglomerate (WPC) on Kangaroo Island, South Australia contains exotic clasts representing a diverse array of lithologies, including metamorphics, chert, sandstone, and abundant carbonates, notably archaeocyath-rich bioclastic limestone. Acetic acid digestion of the WPC bioclastic limestone clasts reveals a diverse shelly fauna. This assemblage includes abundant organophosphatic brachiopods such as Cordatia erinae Brock and Claybourn gen. et sp. nov., Curdus pararaensis, Eodicellomus elkaniformiis, Eohadrotreta sp. cf. E. zhenbaensis, Eoobolus sp., Kyrshabaktella davidii, and Schizopholis yorkensis. Additional shelly taxa include the solenopleurid trilobite Trachoparia? sp., the tommotiids Dailyatia odyssei, Dailyatia decobruta Betts sp. nov., Kelanella sp., and Lapworthella fasciculata, spines of the bradoriid arthropod Mongolitubulus squamifer, and several problematica, such as Stoibostrombus crenulatus and a variety of tubular forms. The upper age limit for the WPC is constrained by biostratigraphic data from the overlying Marsden Sandstone and Emu Bay Shale, which are no younger than the Pararaia janeae Trilobite Zone (Cambrian Series 2, Stage 4). The shelly fossil assemblage from the WPC limestone clasts indicates an upper Dailyatia odyssei Zone (= Pararaia tatei to lower P. janeae trilobite zones), equivalent to the Atdabanian–early Botoman of the Siberian scheme. This contrasts with the previously suggested late Botoman age for the limestone clasts, based on the diverse archaeocyath assemblage. The minor age difference between the WPC and its fossiliferous limestone clasts suggests relatively rapid reworking of biohermal buildups during tectonically-active phases of deposition in the Stansbury Basin.

Cambrian Series 2 shelly fossils from thick carbonate successions in East Antarctica have received limited systematic treatment through the 20th century. Described here are the East Antarctic camenellan tommotiids from the Shackleton Limestone in the Central Transantarctic Mountains and the Schneider Hills limestone in the Argentina Range. This material comes from both newly sampled collections and incompletely described material from older collections. The assemblage supports correlation to the Dailyatia odyssei Zone and Pararaia janeae Trilobite Zone of South Australia, with the newly examined specimens of Dailyatia decobruta from the Shackleton Limestone providing direct correlation to the Mernmerna Formation of the Ikara-Flinders Ranges and White Point Conglomerate of Kangaroo Island. These East Antarctic assemblages include five species referred to Dailyatia, in addition to an undetermined kennardiid species and fragments of the problematic Shetlandia multiplicata. The results further corroborate the notion that fossiliferous carbonate clasts found on King George Island were sourced from the same carbonate shelf as the Shackleton Limestone, with the taxon S. multiplicata found in both units. The Schneider Hills limestone in the Argentina Range has yielded sclerites of Dailyatia icari sp. nov., currently only known from this location. [ABSTRACT FROM AUTHOR]

Tommotiida finds from the Lower Cambrian of the Khairkhan Section located within the Central Tuva trough were characterized for the first time. The assemblages of small shelly fossils are represented by species of the genera typical for the Upper Atdabanian age, such as Tannuolina, Kelanella, Lugoviella, and Microdictyon. Sclerites of four different morphotypes were identified for the Lugoviella ojmuranica species. [ABSTRACT FROM AUTHOR]

The lower Cambrian (Series 2) White Point Conglomerate (WPC) on Kangaroo Island, South Australia contains exotic clasts representing a diverse array of lithologies, including metamorphics, chert, sandstone, and abundant carbonates, notably archaeocyath-rich bioclastic limestone. Acetic acid digestion of the WPC bioclastic limestone clasts reveals a diverse shelly fauna. This assemblage includes abundant organophosphatic brachiopods such as Cordatia erinae Brock and Claybourn gen. et sp. nov., Curdus pararaensis, Eodicellomus elkaniformiis, Eohadrotreta sp. cf. E. zhenbaensis, Eoobolus sp., Kyrshabaktella davidii, and Schizopholis yorkensis. Additional shelly taxa include the solenopleurid trilobite Trachoparia? sp., the tommotiids Dailyatia odyssei, Dailyatia decobruta Betts sp. nov., Kelanella sp., and Lapworthella fasciculata, spines of the bradoriid arthropod Mongolitubulus squamifer, and several problematica, such as Stoibostrombus crenulatus and a variety of tubular forms. The upper age limit for the WPC is constrained by biostratigraphic data from the overlying Marsden Sandstone and Emu Bay Shale, which are no younger than the Pararaia janeae Trilobite Zone (Cambrian Series 2, Stage 4). The shelly fossil assemblage from the WPC limestone clasts indicates an upper Dailyatia odyssei Zone (= Pararaia tatei to lower P. janeae trilobite zones), equivalent to the Atdabanian-early Botoman of the Siberian scheme. This contrasts with the previously suggested late Botoman age for the limestone clasts, based on the diverse archaeocyath assemblage. The minor age difference between the WPC and its fossiliferous limestone clasts suggests relatively rapid reworking of biohermal buildups during tectonically-active phases of deposition in the Stansbury Basin. [ABSTRACT FROM AUTHOR]

Abstract The eccentrothecimorph tommotiid Paterimitra pyramidalis Laurie, 1986, was previously only known from lower Cambrian rocks of the Northern Territory and South Australia. Herein, we document the first occurrence of P. pyramidalis from the Xinji Formation in the Shuiyu section at Ruicheng County, Shanxi Province, located at the southwestern margin of the North China Platform. This represents the first report of a tommotiid taxon from lower Cambrian strata of the North China Platform. All three sclerite types that characterise the scleritome of P. pyramidalis have been recovered and are described, permitting definitive identification to species level. The discovery of P. pyramidalis from the North China Platform not only greatly extends the palaeogeographic range of this distinctive tommotiid taxon, but also supports planktotrophic development of larvae in Paterimitra as a stem group brachiopod. The discovery of P. pyramidalis supports a Cambrian, Epoch 2, late Age 3 to early Age 4 age for the shelly fossil fauna from the Xinji Formation and indicates a close palaeogeographic position between the North China Platform and Australian East Gondwana during the early Cambrian. Graphical abstract Unlabelled Image Highlights • This is the first discovery of tommotiid Paterimitra pyramidalis from the Cambrian Epoch 2 of North China. • This discovery extends the palaeogeographic range of this taxon, supporting planktotrophic development of the larvae. • It indicates a close palaeogeographic position between North China and Australian East Gondwana during the Cambrian. [ABSTRACT FROM AUTHOR]

Three specimens of a new eccentrothecimorph tommotiid are described from the Paralleldal Formation of North Greenland. The specimens are all tubular structures composed of a number of individual sclerites. The sclerites were arranged in rings, which fused to form a rigid tube during ontogeny. The tube has a basal aperture presumably allowing attachment to a hard substrate. In morphology, both individual sclerites and the tubular scleritome are remarkably similar to specimens of Eccentrotheca from South Australia. However, the Greenland specimens are silicified and may have been either weakly mineralised or calcareous in original composition. In this respect they differ from all previously known tommotiids, considerably expanding the ultrastructural disparity of the Tommotiida and allowing comparison to a new range of possible lophotrochozoan fossils. [ABSTRACT FROM AUTHOR]

Among extant animals, Lophotrochozoa accounts for the majority of phyla. 1 This bilaterian clade radiated rapidly during the Cambrian explosion, obfuscating its phylogenetic relationships and rendering many aspects of its early evolution uncertain. Many early lophotrochozoans are known only from isolated skeletal microfossils, "small shelly fossils," often derived from larger animals with complex multi-element skeletons. 2 The discovery of articulated fossils has revealed surprising insights into the animals from which these skeletal pieces were derived, such as paired shells in the mollusc Halkieria. 3 Tommotiids are a key group of phosphatic early skeletal fossils that first appear in the late early Cambrian. 4,5 Although their affinities were previously obscure, discoveries of partial scleritomes and investigations of growth and microstructure 6 provide links with Brachiopoda 7,8 and Phoronida, 9 two of the lophophorate phyla. By contrast, the body plan of camenellan tommotiids remains a palaeontological mystery, with hypothetical reconstructions representing motile, benthic, dorsally armored worms. 4,10 Here, we describe an articulated camenellan (Wufengella bengtsoni gen. et sp. nov.) from the Cambrian Chengjiang Biota, China, revealing the morphology of the scleritome and the first soft tissues from an adult tommotiid. Wufengella carries two dorsal rows of sclerites in a highly asymmetric arrangement, flanked by smaller, cap-shaped sclerites. The scleritome was fringed by iterated fascicles of chaetae and two layers of flattened lobes. Phylogenetic analysis confirms that camenellans occupy a deep branch in lophophorate phylogeny, prior to the acquisition of a sessile lifestyle. Wufengella reveals direct evidence for a metameric body plan reminiscent of annelids early in the evolutionary history of lophophorates. 11,12 [Display omitted] • We describe the first articulated camenellan tommotiid, from the early Cambrian • Camenellans had seriated, annelid-like chaetal bundles and body outgrowths • Early lophophorates were armored, vagile animals prior to becoming sessile • Soft anatomy is vital for understanding the oldest skeletal fossils Guo et al. describe the first known articulated camenellan tommotiid, a group of enigmatic Cambrian animals that have been difficult to classify based on disarticulated microfossils. Camenellans were vagile armored worms, with affinities to living lophophorates (e.g., brachiopods), suggesting a motile last common ancestor. [ABSTRACT FROM AUTHOR]

The camenellan tommotiid Dailyatia is one of the most common fossils in shallow water carbonates from Cambrian Stages 2-4 in South Australia (Arrowie and Stansbury basins). Six species of Dailyatia are documented and new terminology for describing camenellan sclerites is introduced. Dailyatia sclerites are found in three fundamental sclerite types (A-C), each of which may be present in one to three sub-types depending on species. The previously described species Dailyatia ajax Bischoff 1976 and D. macroptera (Tate 1892) are revised and four additional species are described for the first time from South Australia. These include D. odyssei Evans & Rowell 1990, previously known only from Antarctica, and two new species; D. bacata sp. nov. and D. helica sp. nov. as well as a species left under open nomenclature. Two of the recognised species (D. macroptera and D. helica) occur in two different ecophenotypic variants. Species and variants are defined by differences in sclerite types present in the scleritome, sclerite morphology and ornament. The sclerites of Dailyatia are finely laminated with distal expansion of laminae supporting the prominent concentric ribs. The external surface is covered by a fine reticulate network which indicates that the sclerites were at least partly embedded in soft integument. The pattern of incremental growth reveals specific initial and possible gerontic growth stages with unique surface sculptures. Evidence of physical damage and growth disturbances is common in Dailyatia sclerites and many specimens reveal preferential abrasion of the apex. Apical canals are present in all sclerites and are connected to specialised internal apical structures. The internal surface of the sclerites in most species reveals raised platforms and depressed, scar like areas forming unique patterns in each sclerite type, presumably representing muscular attachment. Two specimens revealing ontogenetic fusion of Dailyatia sclerites have been recovered. Based on all available evidence, a new reconstruction of the Dailyatia scleritome is proposed. In the reconstruction, a central row of A and paired B sclerites is flanked on both sides by one or two lateral rows of C sclerites. The exact number of sclerites may vary between species. This reconstruction is based on an assumed slug-like bodyplan and the Dailyatia animal is considered to be a vagrant, benthic animal living in and around archaeocyathan-microbial buildups and in other shallow water carbonate environments. [ABSTRACT FROM AUTHOR]