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Fig. 7 in The Early Cambrian (Botomian) stem group brachiopod Mickwitzia from Northeast Greenland

Fig. 7. Mickwitzia cf. occidens Walcott. Ventral valves; MGUH 26300 (A), + MGUH 26301 (B), MGUH 26302 (C), MGUH 26303 (D), MGUH 26304 (E). A1. Oblique lateral view of early mature valve; scale bar 200 µm. A2. Detail of juvenile shell of A1; scale bar 100 µm. A3. Detail of filar ornamentation with nick−points of A2; scale bar 50 µm. B1. Oblique lateral view of mature valve; scale bar 500 µm. B2. Detail of apex with juvenile shell of B1; scale bar 200 µm. C. Mature valve with exfoliated apex and radiating trails of nick−points; scale bar 500 µm. D. Mature valve showing transition to pustulose mature ornamentation; scale bar 500 µm. E. Detail of ornamentation with radiating trails of nick−points on early mature shell; scale bar 100 µm. All specimens from the Bastion Formation. A, sample GGU 314835; B, sample GGU 314807; C, E, sample GGU 314910; D, sample GGU 314804.

Fig. 5 in The Early Cambrian (Botomian) stem group brachiopod Mickwitzia from Northeast Greenland

Fig. 5. Mickwitzia cf. occidens Walcott, fragment of mature shell MGUH 26298. A. Acrotretoid−type column with clusters of adhering cocci; scale bar 10 µm. B. Acrotretoid−type column entirely filled by centripetal lamination. Note the two single adhering cocci; scale bar 10 µm. C. Detail of single dome−shaped coccus attached to column; scale bar 2 µm. D. Acrotretoid−type column (left) entirely covered by attached and overlapping discoidal bodies (= deformed cocci) and some individual spheroidal cocci; scale bar 10 µm. E. Detail of surface of left column with overlapping discoidal structures; scale bar 2 µm. F. Aborted, dome−shaped acrotretoid−type column, with indications of annulations; scale bar 10 µm. G. Detail of top of aborted column in F, showing a finely platy cover; scale bar 2 µm. H. Cluster of cocci, with indication of asexual binary fission; scale bar 2 µm. I. Detail of central cocci in H, showing platy cover; scale bar 1 µm. J. Detail of cocci−covered lamina and columns; scale bar 5 µm. K. Detail of single spheroidal cocci attached to column; scale bar 2 µm. L. Detail of K, showing possible aperture. Note the platy appearance of the outer surface; scale bar 1 µm. The specimen is from the Ella Island Formation (sample GGU 314816).

Fig. 1 in The Early Cambrian (Botomian) stem group brachiopod Mickwitzia from Northeast Greenland

Fig. 1. Stratigraphical subdivisions of the Lower Cambrian and location map of Northeast Greenland, with simplified stratigraphical logs. Sample numbers and levels indicated.

Fig. 13 in The Early Cambrian (Botomian) stem group brachiopod Mickwitzia from Northeast Greenland

Fig. 13. Inferred distribution of setae (as indicated by nick−points) in juvenile (A) and early mature ventral valves of Mickwitzia cf. occidens Walcott.

Fig. 12 in The Early Cambrian (Botomian) stem group brachiopod Mickwitzia from Northeast Greenland

Fig. 12. Mickwitzia cf. occidens Walcott. A. Fragmentary mature valve (indeterminate) MGUH 26317. A1. Exfoliated interior surface showing numerous acrotretoid−type columns and scattered large tubes, position of A2 and A3 indicated; scale bar 50 µm. A2. Detail of A1 showing single large tube with adhering cocci and numerous acrotretoid−type columns; scale bar 10 µm. A3. Detail of A1 showing numerous acrotretoid−type columns, some of which have a central canal of varying diameter or are completely filled; scale bar 10 µm. A4. Detail of A1 showing lamina perforated by empty large tube (marked by arrow) and +

Fig. 4 in The Early Cambrian (Botomian) stem group brachiopod Mickwitzia from Northeast Greenland

Fig. 4. Mickwitzia cf. occidens Walcott. A. Ventral valve MGUH 26296. A1. Interior of juvenile−early mature ventral valve showing tubular openings surrounded by circular depressions, where non−phosphatic material has been dissolved; scale bar 200 µm. A2. Detail of interior of A1, with recrystallized and secondarily enlarged cocci; scale bar 100 µm. B. Exterior of ventral valve MGUH 26297, showing concentric zones of resistant phosphatic material (cocci) around the tubes result in knobs protruding over the surrounding regions; scale bar 500 µm. All specimens from the Bastion Formation (sample GGU 314905).

Fig. 9 in The Early Cambrian (Botomian) stem group brachiopod Mickwitzia from Northeast Greenland

Fig. 9. Mickwitzia cf. occidens Walcott. Fragmentary mature valves (indeterminate) MGUH 26311 (A), MGUH 26312 (B), MGUH 26313 (C). A1, A2. Pustulose mature ornamentation with low cone−shaped pustules, perforated by the radiating rows of large tubular openings; scale bar 200 µm. A3. Detail of cone−shaped pustules of A, also showing three large tubular openings; scale bar 50 µm. A4. Detail of pyramidal pustules of A1, showing also scattered large tubular openings; scale bar 50 µm. A5. Detail of large tubular opening of A1. Note lack of depressions around the aperture; scale bar 10 µm. A6. Detail of granular surface structure of A1 and pyramidal pustules; scale bar 50 µm. B. Detail of exfoliated surface of mature valve showing numerous openings to acrotretoid−type columns and single large tubular opening; scale bar 20 µm. C1. Section through re−crystallized primary layer with pyramidal pustules; scale bar 20 µm. C2. Detail of primary layer of C1; scale bar 10 µm. All specimens from the Ella Island Formation, sample GGU 314816.

Fig. 8 in The Early Cambrian (Botomian) stem group brachiopod Mickwitzia from Northeast Greenland

Fig. 8. Mickwitzia cf. occidens Walcott. A, B. Ventral valves; MGUH 26305 (A), MGUH 26306 (B). A1. Early mature valve showing beginning pustulose ornamentation; scale bar 500 µm. A2. Detail of pustule of A1; scale bar 20 µm. B1. Mature valve with exfoliated apex showing pustulose ornamentation with offset radiating rows; scale bar 500 µm. B2. Detail of pustulose ornamentation B1; scale bar 200 µm. B3. Oblique lateral view of B1; scale bar 500 µm. C. Dorsal valve MGUH 26307; scale bar 200 µm. All specimens from the Bastion Formation. A, sample GGU 314804; B, sample GGU 314814; C, sample GGU 314905.

Fig. 2. Mickwitzia occidens Walcott. A. Ventral valve MGUH 26294 in The Early Cambrian (Botomian) stem group brachiopod Mickwitzia from Northeast Greenland

Fig. 2. Mickwitzia occidens Walcott. A. Ventral valve MGUH 26294, lateral view of exterior; scale bar 500 µm. B. Ventral valve MGUH 26295, detail of exfoliated exterior with large tube and cocci; scale bar 20 µm. All specimens from the middle member of the Poleta Formation in Indian Springs Canyon, northern Montezuma Range, Esmeralda County, Nevada.

Fig. 9 in The Early Cambrian origin of thylacocephalan arthropods

Fig. 9. Interpretation of possible Early Cambrian thylacocephalans as nektonic organisms living in the lowermost levels of the water column in a shelf marine habitat (max. bottom depth ca. 100–150 m). A. Isoxys (after Vannier and Chen 2000, modified; possible prehensile appendages after Hu 2005). B. Tuzoia (after Vannier et al. in press). C. Zhenghecaris gen. nov. Members of the benthic (1; selkirkiid worms), epibenthic (2; arthropods Fortiforceps and Kunmingella) and nektobenthic communities (3; waptiids); wsi, water−sediment interface. Not to scale.

Fig. 7 in The Early Cambrian origin of thylacocephalan arthropods

Fig. 7. Zhenghecaris shankouensis sp. nov. from Shankou, Yunnan Province, South China, Maotianshan Shale, Lower Cambrian. Line drawings from photographs of the same specimens as shown in Fig. 6. A. Holotype Sk010120, lateral views of part (A1) and counterpart (A2), anterodorsal (A3), and posterodorsal (A4) views. B. Paratype Sk010121, lateral views of part (B1) and counterpart (B2). Arrows point anteriorly.

Fig. 8 in The Early Cambrian origin of thylacocephalan arthropods

Fig. 8. General morphology of a present−day bivalved arthropods exemplified by the myodocopid ostracod Leuroleberis surugaensis (Cylindroleberididae) from the Pacific coast of Japan. L. surugaensis buries itself in sediment and can swim in the water column. A. X−Ray Microtomographs of the animal (specimen FSL 526005) in left lateral (A1), posterior (A2), and ventral (A3) views, complete specimen observed in life−position, immersed in 70% alcohol; body and appendages present but not detected by X−rays. B. SEM micrograph of body (B1, left valve removed) and external ornament (B2, left valve) of specimen FSL 526006. C. Longitudinal section through lateral eyes and gills (microtomized paraffin section); specimen FSL 526007. Abbreviation: a2, second antenna.

Fig. 3 in The Early Cambrian origin of thylacocephalan arthropods

Fig. 3. Size range of thylacocephalans (Lower Cambrian to Upper Cretaceous). 1, Zhenghecaris gen. nov.; 2, Ainiktozoon; 3, undescribed thylacocephalan (Mikulic et al. 1985); 4, 5, Concavicaris (2 different species represented); 6, Harrycaris; 7, Convexicaris; 8, Coreocaris; 9, Ankitokazocaris; 10, Yangzicaris; 11, Atropicaris; 12, Microcaris; 13, 14, Ostenocaris (2 different species represented); 15, Austriocaris; 16, Rugocaris; 17; Paraostenia; 18; Kilianocaris; 19, Dollocaris; 20, Clausocaris; 21, Mayrocaris; 22, 23, Protozoea (2 different species represented); 24, Pseuderichthus; 25, Thylacocephalus. C., Cambrian; Car., Carboniferous; Cret., Cretaceous; Dev., Devonian; Jur., Jurassic; L., Lower; M., Middle; Mi., Mississippian; O., Ordovician; P., Permian; Pe., Pennsylvanian; S., Silurian; Tr., Triassic; U., Upper. Carapace outlines from original publications (see references in Table 1).

Fig. 1. Mesozoic thylacocephalans. A–C. Dollocaris ingens Van Straelen, 1923 in The Early Cambrian origin of thylacocephalan arthropods

Fig. 1. Mesozoic thylacocephalans. A–C. Dollocaris ingens Van Straelen, 1923, Callovian, La Voulte, France. FSL 170759, general view (A1) and detail (A2) of visual surface. B. Three−dimensionally preserved specimen showing a pair of bulbous eyes, in left lateral (B1) and frontal (B2) views (collection of the Musée d'Histoire Naturelle, Lyon, specimen number in−progress). C. IPM R 62002, specimen showing well−preserved raptorial appendages. D. Mayrocaris bucculata Polz, 1994, general view of paratype (specimen 93032701 from Polz 1994: pl. 1: 3, courtesy S. Secrétan).

Fig. 4 in The Early Cambrian origin of thylacocephalan arthropods

Fig. 4. Simplified reconstructions showing the general morphology of thylacocephalan arthropods in left lateral (subscripted with "1"), frontal (subscripted with "2"), and ventral (subscripted with "3") views. A. Dollocaris ingens (Middle Jurassic, La Voulte, France; modified from Secrétan 1985). B. Clausocaris lithographica (Upper Jurassic, Solnhofen, Germany). C. Zhenghecaris shankouensis gen. et sp. nov. (Lower Cambrian, Maotianshan Shale biota, China). Not to scale. A and B modified from Secrétan 1985 and Polz 1990, respectively.

Fig. 2. Fossil locality and depositional environment. A in The Early Cambrian origin of thylacocephalan arthropods

Fig. 2. Fossil locality and depositional environment. A. Simplified paleogeographic map of the Yangtze Platform during the Sinian–Cambrian boundary showing main facies distribution (asterisk for fossil locality). B. Alternating siltstones−mudstones layers at Shankoucun (Maotianshan Shale, Lower Cambrian). Map after Zhu et al. (2003; simplified). bg, background mudstone; se, single−event mudstone (see explanation in text).

Fig. 5 in The Early Cambrian origin of thylacocephalan arthropods

Fig. 5. Hou (1999)'s "large" bivalved arthropods from the Lower Cambrian Maotianshan Shale, China). A. Forfexicaris valida with soft parts. B. Yunnanocaris megista (soft anatomy unknown). C. Occacaris oviformis with soft parts. Simplified after Hou (1999: figs. 2, 4) and Hou et al. (2004: fig. 16.17). Eyes in dark grey.

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FIG. 2 in New archaeocyath genus from the early Cambrian of the western Anti-Atlas, Morocco

FIG. 2. — Fouanoucyathus tafraoutiensis El Bakhouch & Kerner, n. gen., n. sp., holotype AA-FOU-CI-2 from section FO.IS8: A, transverse view of specimen prior to preparation;B, transverse section showing wall and septal porosity (inner wall at right);C, detail of longitudinal section showing the outer and inner walls with canals and septal porosity;D, detail of longitudinal section showing inner wall porosity (central cavity at right);E, detail of longitudinal section showing outer wall porosity (intervallum at right); F, longitudinal section showing wall, septal porosity and a synapticular tabulae (inner wall at right). Scale bars: A, 9 mm; B, 0.5 mm; C, E, F, 1 mm; D, 0.2 mm.

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FIG. 5 in New archaeocyath genus from the early Cambrian of the western Anti-Atlas, Morocco

FIG. 5. — Fouanoucyathus tafraoutiensis El Bakhouch & Kerner, n. gen., n. sp., paratype AA-FOU-CI-1 from section FO.IS4: A, longitudinal view of specimen prior to preparation; B, oblique transverse section showing details of walls and septa porosity; C, longitudinal section (inner wall at right); D, detail of C showing inner wall porosity (central cavity at right); E, detail of C showing outer wall porosity. Scale bars: A, 4 mm; B, 0.4 mm; C, 1.5 mm; D, 1 mm; E, 0.3 mm.