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Carinachitids from the lower Cambrian Kuanchuanpu Formation in South China. (1) Triradiate Emeiconularia amplicanalis Liu et al., 2005. (2) Pentamerous Pentaconularia ningqiangensis Liu et al., 2011. (1, 2) Courtesy of Y.H. Liu. (3-6) Tetraradiate Carinachites spinatus Qian, 1977. (3, 4) ELISN93-157, showing the displacement between neighboring arcuate ribs, which are connected in the middle by striations. Both the faces and ribs widen slightly toward the apertural end of the skeleton. (5) ELISN93-45. (6-12) ELISN148-52. (6, 7) Lateral view of the tube. (8, 9) Close-up of the tube aperture shows one of the plicate apertural lobes being elevated above the others. (10) The elevated, plicate apertural lobes with converging striated folds. (11) Single plicate apertural lobe with converging striated folds and the corner sulci with parallel striations. (12) Close-up of (11) showing secondary cracks on the striated surface. IR = interradius; PR = perradius; cs = corner sulci; pal = plicate apertural lobes; st = striations; tr = transverse ribs; ts = thorn-like spines.
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The early Cambrian Carinachitidae, a family in the subclass Conulata, are intriguing and important small shelly fossils. Their gently tapering, tube-shaped skeletons consist of convex faces separated from each other by broad, deep corner sulci, and they exhibit triradial, pentaradial, or predominantly tetraradial symmetry. However, the morphology o...
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... are an important component of early Cambrian SSFs in South China (Conway Morris and Chen, 1992). Their gently conical skeletal tubes exhibit several (three to five) transversely ribbed faces separated from each other by wide and deep corner sulci that usually bear fine transverse wrinkles (tw) (Fig. 1). To date, three genera and six species of carinachitids-Emeiconularia trigemme Qian in Qian et al., 1997; E. amplicanalis Liu et al., 2005 ( Fig. 1.1); Pentaconularia ningqiangensis Liu et al., 2011 (Fig. 2); Carinachites spinatus Qian, 1977 (Figs. 3-5); C. tetrasulcatus Jiang in Luo et al., 1982;and C. curvatornatus Chen, 1982-have ...
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... Their gently conical skeletal tubes exhibit several (three to five) transversely ribbed faces separated from each other by wide and deep corner sulci that usually bear fine transverse wrinkles (tw) (Fig. 1). To date, three genera and six species of carinachitids-Emeiconularia trigemme Qian in Qian et al., 1997; E. amplicanalis Liu et al., 2005 ( Fig. 1.1); Pentaconularia ningqiangensis Liu et al., 2011 (Fig. 2); Carinachites spinatus Qian, 1977 (Figs. 3-5); C. tetrasulcatus Jiang in Luo et al., 1982;and C. curvatornatus Chen, 1982-have been reported from the Kuanchuanpu Formation and equivalent horizons in South China (Qian, 1977;He, 1987;Conway Morris and Chen, 1992;Qian et al., 1997; ...
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... of Carinachites spinatus were obtained from samples of phosphatic limestone collected from the Kuan- chuanpu Formation in southern Shaanxi Province, South China, and digested in 10% acetic acid. Specimens ELISN148-52, ELISN93-45, ELISN93-157, ELISN19-20, ELISN23-240, and ELISN12-154 come from the Shizhonggou section in Ningqiang County, while specimen XX30-127 is from the Yangjiagou section in Xixiang County (for localities, see Steiner et al., 2007, fig.1). All specimens were coated with gold and then imaged using an FEI Quanta 400 FEG scanning electron microscope (SEM). ...
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... convex faces separated from each other by deep corner sulci (Figs. 1.3-1.6, 2.6). Each face usually bears a longitudinal series of arcuate transverse ribs that range in shape from simple welts to more complex folds (Conway Morris and Chen, 1992). The distance between adjacent ribs increases slightly toward the wide or oral end of the tube (Fig. 1.3). Near the facial midline, the region between any two adjacent ribs exhibits several, mutually parallel or irregular, longitudinal striated folds that in most cases are separated from each other by an inconspicuous shallow groove ( Fig. ...
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... Chen, 1992). The distance between adjacent ribs increases slightly toward the wide or oral end of the tube (Fig. 1.3). Near the facial midline, the region between any two adjacent ribs exhibits several, mutually parallel or irregular, longitudinal striated folds that in most cases are separated from each other by an inconspicuous shallow groove ( Fig. ...
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... transverse ribs in some specimens are arcuate near the distal end and as wide as the faces (Fig. 1.3, 1.4), while in other specimens the ribs consist of a prominent, sharp, thorn-like spine (ts) such as those exhibited by specimens ELISN93-45 ( Fig. 1.5) and ELISN148-52 ( Fig. 1.6). The ribs on any two neighboring faces usually are located at the same levels above the apex, but some ribs exhibit longitudinal offset ( Fig. 1.3, 1.4) (Conway ...
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... transverse ribs in some specimens are arcuate near the distal end and as wide as the faces (Fig. 1.3, 1.4), while in other specimens the ribs consist of a prominent, sharp, thorn-like spine (ts) such as those exhibited by specimens ELISN93-45 ( Fig. 1.5) and ELISN148-52 ( Fig. 1.6). The ribs on any two neighboring faces usually are located at the same levels above the apex, but some ribs exhibit longitudinal offset ( Fig. 1.3, 1.4) (Conway Morris and Chen, 1992). In addition, the ribs of some specimens are offset along the facial midline (Conway Morris and Chen, 1992, fig. 6.1). ...
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... transverse ribs in some specimens are arcuate near the distal end and as wide as the faces (Fig. 1.3, 1.4), while in other specimens the ribs consist of a prominent, sharp, thorn-like spine (ts) such as those exhibited by specimens ELISN93-45 ( Fig. 1.5) and ELISN148-52 ( Fig. 1.6). The ribs on any two neighboring faces usually are located at the same levels above the apex, but some ribs exhibit longitudinal offset ( Fig. 1.3, 1.4) (Conway Morris and Chen, 1992). In addition, the ribs of some specimens are offset along the facial midline (Conway Morris and Chen, 1992, fig. 6.1). Figure 4. 3D reconstructions of ...
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... wide as the faces (Fig. 1.3, 1.4), while in other specimens the ribs consist of a prominent, sharp, thorn-like spine (ts) such as those exhibited by specimens ELISN93-45 ( Fig. 1.5) and ELISN148-52 ( Fig. 1.6). The ribs on any two neighboring faces usually are located at the same levels above the apex, but some ribs exhibit longitudinal offset ( Fig. 1.3, 1.4) (Conway Morris and Chen, 1992). In addition, the ribs of some specimens are offset along the facial midline (Conway Morris and Chen, 1992, fig. 6.1). Figure 4. 3D reconstructions of Cambrian carinachitids with a hypothetical apical tip. (1-3) Lateral, oblique, and oral views, respectively, of Emeiconularia; (4-6) lateral, oblique, and ...
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... ELISN93-45 ( Fig. 1.5) and ELISN148-52 ( Fig. 1.6). The ribs on any two neighboring faces usually are located at the same levels above the apex, but some ribs exhibit longitudinal offset ( Fig. 1.3, 1.4) (Conway Morris and Chen, 1992). In addition, the ribs of some specimens are offset along the facial midline (Conway Morris and Chen, 1992, fig. 6.1). Figure 4. 3D reconstructions of Cambrian carinachitids with a hypothetical apical tip. (1-3) Lateral, oblique, and oral views, respectively, of Emeiconularia; (4-6) lateral, oblique, and oral views, respectively, of Carinachites spinatus; (7-9) lateral, oblique, and oral views, respectively, of Pentaconularia. The apertural region, ...
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... tip. (1-3) Lateral, oblique, and oral views, respectively, of Emeiconularia; (4-6) lateral, oblique, and oral views, respectively, of Carinachites spinatus; (7-9) lateral, oblique, and oral views, respectively, of Pentaconularia. The apertural region, preserved only in the relatively large specimen ELISN148-52, is superficially dome-shaped ( Fig. 1.6-1.9). The maximum diameter of the tube is approximately 1.3 mm, but near its apertural end the tube tapers rapidly, with the faces curving smoothly toward the longitudinal axis of the tube and becoming more or less perpendicular to it. Close to the longitudinal axis, the faces and intervening corner sulci are inclined toward the aboral end ...
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... The maximum diameter of the tube is approximately 1.3 mm, but near its apertural end the tube tapers rapidly, with the faces curving smoothly toward the longitudinal axis of the tube and becoming more or less perpendicular to it. Close to the longitudinal axis, the faces and intervening corner sulci are inclined toward the aboral end of the tube (Fig. 1.6, 1.7, 1.9). Present on each face, at the summit of the aperture, is a triangular tongue-shaped structure, and the distal ends of the faces almost meet near the longitudinal axis of the tube, leaving just a narrow central opening. One of the tongue-shaped structures projects much farther than the others beyond the aperture ( Fig. 1.6). The ...
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... of the tube (Fig. 1.6, 1.7, 1.9). Present on each face, at the summit of the aperture, is a triangular tongue-shaped structure, and the distal ends of the faces almost meet near the longitudinal axis of the tube, leaving just a narrow central opening. One of the tongue-shaped structures projects much farther than the others beyond the aperture ( Fig. 1.6). The tongue-shaped structures are not flat features but rather fold-like structures having two main, arched sides separated by two flanks. For this reason, we term the tongue-shaped structures 'plicate apertural lobes' (pal). The vertical abapertural side of the apertural lobes extends far into the apertural opening and exhibits a ...
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... but rather fold-like structures having two main, arched sides separated by two flanks. For this reason, we term the tongue-shaped structures 'plicate apertural lobes' (pal). The vertical abapertural side of the apertural lobes extends far into the apertural opening and exhibits a medial subtriangular groove bordered by two elevated flanks ( Fig. 1.8, 1.9). The abapertural side is either flat or outwardly convex with a central ridge, and there are many longitudinal striations on the two sides. These striations converge on the tip of the lobes, and there are some oblique, irregular cracks on the striated surface ( Fig. 1.11, 1.12). Situated peripheral to the apertural lobes are four ...
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... a medial subtriangular groove bordered by two elevated flanks ( Fig. 1.8, 1.9). The abapertural side is either flat or outwardly convex with a central ridge, and there are many longitudinal striations on the two sides. These striations converge on the tip of the lobes, and there are some oblique, irregular cracks on the striated surface ( Fig. 1.11, 1.12). Situated peripheral to the apertural lobes are four longitudinal rows of nearly evenly spaced, nose-shaped, thorn-like spines aligned along the lateral sides of the faces. In addition, the distance between the apertural lobes and the marginal thorn-like spines is approximately equal to the distance between adjacent thorn-like spines. ...
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... which is more or less perpendicular to the lateral faces, is concave aborally. The abapertural side, like the bridge of a nose, is inclined at approximately 30º to the lateral faces. The four corner sulci, which are substantially lower than the apertural lobes, follow the inward foldings of the adjacent faces and extend far into the tube cavity ( Fig. 1.9). The external surface of the sulci is highly and irregularly folded and exhibits fine parallel striations. The summit of the four corner sulci is evidently lower than that of the faces ( Fig. 1.9). Clearly, then, the tube aperture, including the inwardly folded portion, is a smooth continuation of the faces and corner ...
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... sulci, which are substantially lower than the apertural lobes, follow the inward foldings of the adjacent faces and extend far into the tube cavity ( Fig. 1.9). The external surface of the sulci is highly and irregularly folded and exhibits fine parallel striations. The summit of the four corner sulci is evidently lower than that of the faces ( Fig. 1.9). Clearly, then, the tube aperture, including the inwardly folded portion, is a smooth continuation of the faces and corner ...
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... the granular layer was thought to have been originally organic but later replaced by diagenetic apatite ). Although we are mindful of possible preservational artefacts, Micro-CT imaging revealed that the thickness of the tube wall in specimen ELISN148-52 appears to vary, and that the apertural walls are much thinner than the lateral tube walls (Fig. 2.1a, 2.1c, 2.1e). High magnification imaging revealed a single-layered wall in the apertural region ( Fig. 2.1c) and bilayered lateral tube walls (white arrows in Fig. 2.1a, 2.1g). In addition, the facial walls are thicker than those of the corner sulci ( Fig. 2.1a, 2.1g). Finally, both the thorn-like spines and the apertural lobes are ...
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... Although we are mindful of possible preservational artefacts, Micro-CT imaging revealed that the thickness of the tube wall in specimen ELISN148-52 appears to vary, and that the apertural walls are much thinner than the lateral tube walls (Fig. 2.1a, 2.1c, 2.1e). High magnification imaging revealed a single-layered wall in the apertural region ( Fig. 2.1c) and bilayered lateral tube walls (white arrows in Fig. 2.1a, 2.1g). In addition, the facial walls are thicker than those of the corner sulci ( Fig. 2.1a, 2.1g). Finally, both the thorn-like spines and the apertural lobes are hollow ( Fig. ...
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... 2.1a, 2.1c, 2.1e). High magnification imaging revealed a single-layered wall in the apertural region ( Fig. 2.1c) and bilayered lateral tube walls (white arrows in Fig. 2.1a, 2.1g). In addition, the facial walls are thicker than those of the corner sulci ( Fig. 2.1a, 2.1g). Finally, both the thorn-like spines and the apertural lobes are hollow ( Fig. ...
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... within the tube is a short, subcylindrical mass measuring ~200 µm in diameter and 400 µm in length. The upper part of this feature is in direct contact with the inward folds of the faces and corner sulci ( Fig. 2.1b-e), and it is connected to the lateral tube wall by numerous fine, straight filaments (mmf) (Fig. 2.1a-g). No additional details of the subcylindrical mass can be ...
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... multiple thorn-like spines on specimens ELISN93-45 ( Fig. 1.5) and ELISN148-52 ( Fig. 1.6) indicate that the morphology of the ribs on the faces of a single individual is essentially uniform and constant, without gradual transforma- tion from welts to arcuate ribs or other, more complex folds. Probably, this replacement began at the basal end of the tube and continued to the upper part without ...
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... multiple thorn-like spines on specimens ELISN93-45 ( Fig. 1.5) and ELISN148-52 ( Fig. 1.6) indicate that the morphology of the ribs on the faces of a single individual is essentially uniform and constant, without gradual transforma- tion from welts to arcuate ribs or other, more complex folds. Probably, this replacement began at the basal end of the tube and continued to the upper part without metamorphosis. If this ...
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... addition to sequential adoral addition of ribs on the faces, growth of the Carinachites tube also involved increase in the diameter of the tube and the width of the corner sulci. Along the longitudinal axis, the corner sulcus expands gradually toward the aperture (Fig. 1.5). In the most complete specimen (ELISN93-45), which however lacks the apex and apertural margin, at least 35 ribs are present on each face (Fig. 1.5). If the tube could grow up to 1.3 mm in width, as indicated by specimen ELISN148-52 ( Fig. 1.6), then we infer that a single face may have contained at least 130 ribs over a total length ...
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... of the Carinachites tube also involved increase in the diameter of the tube and the width of the corner sulci. Along the longitudinal axis, the corner sulcus expands gradually toward the aperture (Fig. 1.5). In the most complete specimen (ELISN93-45), which however lacks the apex and apertural margin, at least 35 ribs are present on each face (Fig. 1.5). If the tube could grow up to 1.3 mm in width, as indicated by specimen ELISN148-52 ( Fig. 1.6), then we infer that a single face may have contained at least 130 ribs over a total length of approximately 25 mm. With regard to the apertural extension model mentioned in the preceding, neighboring ribs at the same level indicate that the ...
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... the corner sulci. Along the longitudinal axis, the corner sulcus expands gradually toward the aperture (Fig. 1.5). In the most complete specimen (ELISN93-45), which however lacks the apex and apertural margin, at least 35 ribs are present on each face (Fig. 1.5). If the tube could grow up to 1.3 mm in width, as indicated by specimen ELISN148-52 ( Fig. 1.6), then we infer that a single face may have contained at least 130 ribs over a total length of approximately 25 mm. With regard to the apertural extension model mentioned in the preceding, neighboring ribs at the same level indicate that the plicate apertural lobes were replaced synchronously by new ones (Fig. 4.4-4.6). In contrast, ...
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... 1997), and in most fragmentary specimens, the sulci exhibit secondary breakage. Probably in life the flexible corner sulci served as buffer zones that prevented tearing of the tube during diachronous replacement of the ribs on neighboring faces. The reason for longitudinal offset of the ribs along the facial midline (Conway Morris and Chen, 1992, fig. 6.1) remains unclear, though probably each apertural lobe was formed asynchronously by two adjacent subunits of soft tissue. It is important to note that longitudinal offset or asynchronous displacement of the ribs also can be seen on hexangulaconulariids, but it has never been observed in ...
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... and growth of other carinachitids.-Since the ribs most likely constitute displaced plicate lobes, the four uniform plicate lobes in tetraradiate Carinachites spinatus correspond to the four rows of lateral facial ribs. Similarly, triradiate Emeiconularia and pentamerous Pentaconularia ningqiangensis Liu et al., 2011 most likely possessed three (Fig. 4.1, 4.2) and five centripetal plicate lobes (Fig. 4.7-4.9), respectively. Similarly, specimens with arcuate ribs reflect the presence of a set of centripetal arcuate lobes in the apertural region. Nevertheless, the apertural region of Carinachites tetrasulcatus (Chen, 1982) is difficult to reconstruct as its ribs are low and inconspicuous ...
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... in Conway Morris and Chen, 1992) and the relative rigidity of the entire tube wall, (2) the high abundance of fragmentary specimens of carinachitids and the extremely rare preservation of their aperture, and (3) probable variation in mechanical properties between the different layers as reflected in the secondary cracks on the tube surface ( Fig. 1.11, 1.12). However, because the relic soft tissue is much smaller in diameter than the host tube, the sides of the soft body may not have been in direct contact with the lateral tube wall. How the organic or inorganic material was deposited on the inner surface of the outer layer remains ...
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... noted previously (He, 1987), the similarities among the skeletons of olivooids, carinachitids, hexangulaconulariids, and Paleozoic con- ulariids are striking (Table 1). They include: (1) possession of a superficially cone-shaped tube that almost completely enveloped the soft tissue (Qian and Bengtson, 1989;Sendino et al., 2011); (2) tube with serially repeated transverse and longitudinal wrinkles (Qian and Bengtson, 1989) representing periodic growth by oral addition (Brood, 1995); (3) fine, regularly spaced longitudinal striations, ~5-10 µm in width, as one of typical features of Olivooides tubes (e.g., Yue and Bengtson, 1999, fig. 2D; Steiner et al., 2014, fig. ...
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... 12.14), are present also on the corner surface of Carinachites tetrasulcatus (e.g., Conway Morris and Chen, 1992, fig. 9.15, 9.16); (4) tube tapered in the apertural region (Qian and Bengtson, 1989), where the tube aperture is folded inward (e.g., Brood, 1995;Steiner et al., 2014); (5) all tubes exhibit distinct apical and abapical regions ( Fig. 1.8) (Van Iten et al., 2010), although the carinachitid apex is unknown yet; and (6) radial symmetry, a characteristic that is a link to the medusozoans, is well represented by all four ...
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... 12.14), are present also on the corner surface of Carinachites tetrasulcatus (e.g., Conway Morris and Chen, 1992, fig. 9.15, 9.16); (4) tube tapered in the apertural region (Qian and Bengtson, 1989), where the tube aperture is folded inward (e.g., Brood, 1995;Steiner et al., 2014); (5) all tubes exhibit distinct apical and abapical regions ( Fig. 1.8) (Van Iten et al., 2010), although the carinachitid apex is unknown yet; and (6) radial symmetry, a characteristic that is a link to the medusozoans, is well represented by all four families. ...
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... outwardly bulging faces, and later ontogenetic thickening, thus providing stronger support for the soft body. The face-corner configuration in carinachitids also reflects an incipient differ- entiation of the meridian planes. The apertural lobes among different taxa of olivooids vary greatly in morphology. Thus, unlike Olivooides multisulcatus ( Fig. 5.1-5.3), Quadrapygites andO. mirabilis Yue, 1984 in Xing et al., 1984 lack clear differentiation in size between the principle apertural lobes and the adradial apertural lobes. By contrast, carinachitids exhibit only the principle apertural lobes. The corner sulci in carinachitids may correspond to the adradial apertural lobes in olivooids. ...
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... symmetry. However, biradial symmetry, common in conular- iids, has not been observed in carinachitids. In addition, the corners of some conulariids, for example Eoconularia loculata (Wiman, 1895in Jerre, 1994, are much thicker than the faces (Jerre, 1994), contrasting with the relatively thickened faces of carinachitid Emeiconularia trigemme (Fig. 2.1b). Moreover, in addition to plicate apertural lobes (Ford et al., 2016), conulariids Table 1. Morphological comparisons among olivooids, hexangulaconulariids, carinachitids, and ...
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... addition, the corners of some conulariids, for example Eoconularia loculata (Wiman, 1895in Jerre, 1994, are much thicker than the faces (Jerre, 1994), contrasting with the relatively thickened faces of carinachitid Emeiconularia trigemme (Fig. 2.1b). Moreover, in addition to plicate apertural lobes (Ford et al., 2016), conulariids Table 1. Morphological comparisons among olivooids, hexangulaconulariids, carinachitids, and conulariids. ...
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... The most distinctive characteristics of medusozoans are their radial symmetry and their ability to swim . Paleontologists have found numerous medusozoans in the early Ma) (Dong et al., 2013;Han et al., 2013;Liu et al., 2014a;Steiner et al., 2014;Dong et al., 2016;Liu et al., 2017;Wang et al., 2017;Shao et al., 2018b;Han et al., 2018;Shao et al., 2019a;. In the Zhangjiagou Section, South China, various Fortunian radial animals were found such as Olivooides, Quadrapyrgites, and Hexaconularia (Conway Morris and Chen, 1992;Van Iten et al., 2006;Van Iten et al., 2010;Liu et al., 2014b;Van Iten et al., 2014;Liu et al., 2017). ...
... The possible polypoid cnidarians from the Fortunian stage correspond to Anabaritidae (Conway Morris and Chen, 1989;Kouchinsky et al., 2009), Hexangulaconulariidae (Qian and Bengtson, 1989;Van Iten et al., 2010;Steiner et al., 2014), Carinachitidae (Qian, 1977;Conway Morris and Chen, 1992;Yue and Bengtson, 1999;Liu et al., 2005;Liu et al., 2011;Han et al., 2018), Olivooidae (Steiner et al., 2010;Steiner et al., 2014;Han et al., 2016a;Han et al., 2016b) and Family uncertain (Steiner et al., 2004a;Dong et al., 2013;Shao et al., 2015). They had comparable radial symmetry, tube morphology, and developmental cycles. ...
Microscopic medusozoans from the Cambrian Fortunian stage of South China are well known for their exceptionally preserved embryos and elongated tubes. However, additional details of their morphology remain unclear. This paper describes new medusozoan fossils showing the whole apical complement and covering the morphological integrity of Qinscyphus. The apical part of Qinscyphus is considered to be soft during early ontogeny, and the inverted pentagonal pyramid may gradually form with growth and development. This discovery of the apical complement of Qinscyphus is novel and essential to complement the external morphology of early medusozoan fossils. More importantly, the new specimens have different annuli with triangular thickenings, providing a more comprehensive view on the developmental sequence of Qinscyphus. Therefore, this work allows a better understanding of early medusozoans ecology and evolution.
... Terminology-The anatomical terminology used herein mostly follows the precedents in Conway Morris and Chen (1992), Van Iten et al. (2010), Han et al. (2018), and Guo et al. (2020aGuo et al. ( , 2021a. ...
Hexangulaconulariids, a family of biradially symmetrical medusozoan cnidarians, have been widely reported from the Lower Cambrian of South China. The four currently recognized genera of hexangulaconulariids differ from each other mainly in the number of faces in the abapical region of the periderm. However, previously published illustrations of the monospecific type genus, Hexangulaconularia, clearly show two distinct morphotypes, one with six faces and the other with 10. Specimens with 10 faces are herein reassigned to the genus Decimoconularia. In addition, the new species D. anisfacialis is described from the Kuanchuanpu Formation (Cambrian Fortunian Stage) in the Kuanchuanpu and Shizhonggou sections in Ningqiang County, southern Shaanxi Province, China. Also described are additional specimens of H. formosa from the same formation in the Zhangjiagou section in Xixiang County, southern Shaanxi Province, and from Member 2 of the Yanjiahe Formation (Cambrian Fortunian Stage) in western Hubei Province. The discovery of D. anisfacialis extends the known stratigraphical range of Decimoconularia, now composed of two species, downward from Cambrian Stage 2 into the Fortunian Stage. Additionally, certain specimens previously assigned to H. formosa are reassigned to D. anisfacialis. The diagnoses of Hexangulaconularia, Decimoconularia, and Hexangulaconulariidae are emended accordingly. In accordance with the rule of time priority, the previously designated type genus and species, Hexaconularia He and Yang, 1986 and Hexaconularia sichuanensis He and Yang, 1986, are replaced herein by Hexangulaconularia He, in Xing et al., 1983.
... The lower Cambrian fossil record of triradial organisms includes some carinachitids (e.g., Emeiconularia; Qian et al., 1997;Han et al., 2017). In contrast to the latter, Ilankirus has the greater apical angle and lacks deep longitudinal grooves separating the faces, and carries specific surface sculpture (Conway Morris and Chen, 1992;Qian et al., 1997;Han et al., 2017). ...
... The lower Cambrian fossil record of triradial organisms includes some carinachitids (e.g., Emeiconularia; Qian et al., 1997;Han et al., 2017). In contrast to the latter, Ilankirus has the greater apical angle and lacks deep longitudinal grooves separating the faces, and carries specific surface sculpture (Conway Morris and Chen, 1992;Qian et al., 1997;Han et al., 2017). Some of the Cambrian orthothecid hyoliths also had pyramidal elongated shells with a triangle-shaped cross section (Missarzhevsky, 1989;Malinky, 2009). ...
... The early Cambrian carinachitids, interpreted as a sister group of conulariids within scyphozoans Guo et al., 2021), share some morphological features with the anabaritids: minute size and elongated (nearly tubular) shape; development of the radial symmetry by sharp and deep invagination of longitudinal furrows at the corners (e.g., Conway Morris and Chen, 1992;Qian et al., 1997;Han et al., 2017). Although most carinachitids are tetraradial, triradial taxa are also known (Emeiconularia) (Qian et al., 1997). ...
In the early Cambrian fossil record, triradial symmetry is typical for anabaritids and occurs among carinachitids. The former are an extinct group of minute benthic cnidarians covered with a calcareous tubular exoskeleton. The origin of the anabaritids is poorly understood, but previously reported triradial pyramid-shaped steinkerns and molds of the oldest conulariids, Vendoconularia , from the upper Ediacaran of the White Sea region suggested the anabaritids were closely related to conulariids. However, triradial symmetry could originate independently in different lineages in the late Ediacaran and early Cambrian. Herein we describe a new taxon, Ilankirus kessyusensis new genus new species, from the base of the Cambrian Stage 2 of the Olenek Uplift (Siberian Platform). These fossils occur as ornamented steinkerns in the shape of trilateral pyramids and lack any relics of a mineralized exoskeleton. Abundant plastic deformations and fractures of the casts suggest the organism was weakly if at all mineralized. The steinkerns are encrusted with a thin patina of iron-rich chlorite (chamosite) formed because of a multistage diagenetic replacement of authigenic glauconite (glauconite–berthierine–chamosite) under reducing conditions of oxygen-depauperate pore- and seawater. Both lacking two major autapomorphies of the crown-group conulariids (mineralized periderm and quadrate cross section of the oral region of the periderm), the late Ediacaran triradial Vendoconularia and Terreneuvian Ilankirus represent stem-group conulariids.
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... 720-635Ma). Three families of putative medusozoan cnidarians, the carinachitiids, hexangulaconulariids, and olivooids, occur in early Cambrian strata of South China (Conway Morris and Chen, 1992;Dong et al., 2013Dong et al., , 2016Han et al., 2013Han et al., , 2018Steiner et al., 2014;Guo et al., 2020aGuo et al., , b, 2021a. The hexangulaconulariids (Family Hexangulaconulariidae He, 1987) are characterized by a biradially symmetrical periderm having distinct apical and abapical portions (Conway Morris and Chen, 1992;Van Iten et al., 2006, 2010Guo et al., 2020aGuo et al., , 2021a. ...
... Terminology.-Anatomical terminology used herein mostly follows precedents to be found in Conway Morris and Chen (1992), Van Iten (2010), Han et al., (2018), and Guo et al. (2020aGuo et al. ( , 2021a. ...
Hexangulaconulariids, an extinct family of medusozoan Small Shelly Fossils, were a conspicuous component of early Cambrian, shallow marine platform communities of South China. Described herein is Septuconularia crassiformis sp. nov. from Bed 5 of the Yanjiahe Formation (Cambrian Stage 2) in the Three Gorges area of Hubei Province. The new species differs from the type and only other known species, S. yanjiaheensis, in the shape of the abapical portion and in the degree of curvature of the adapertural margin. The anatomy of the apical portion of the new species is unknown. The diagnosis of the genus Septuconularia is emended, and the spatio-temporal distribution of hexangulaconulariids in South China is summarized. Finally, S. yanjiaheensis, with its slit-like aperture and very narrow transverse cross section, may have been better adapted to the shallow platform environment than the broader S. crassiformis, which appears to have been less common than the type species.
... 535 Ma) from Ningqiang County, southern Shaanxi Province of central China. High diversity and disparity of soft-bodied cnidarians (see Han et al., 2017b) and scalidophoran worms are revealed to complement previously reported basal deuterostomes (Han et al., 2017a). The ecological dominance during the Fortunian is largely represented by abundant radiate clades, especially cnidarians and ctenophores, along with an array of tubes or conical fossils mainly belonging to lophotrochozoans that make up a 'tube world' sensu Budd and Jackson (2016). ...
New evolutionary and ecological advances in deciphering the Cambrian explosion of animal life - Volume 92 Special Issue - Zhifei Zhang, Glenn A. Brock
Corumbella is a terminal Ediacaran tubular, benthic fossil of debated morphology, composition and biological affinity. Here, we show that Corumbella had a biomineralized skeleton, with a bilayered construction of imbricated calcareous plates and rings (sclerites) yielding a cataphract organization, that enhanced flexibility. Each sclerite likely possessed a laminar microfabric with consistent crystallographic orientation, within an organic matrix. An original aragonitic mineralogy is supported by relict aragonite and elevated Sr (mean = ca. 11,800 ppm in central parts of sclerites). In sum, the presence of a polarisation axis, sclerites with a laminar microfabric, and a cataphract skeletal organisation reminiscent of early Cambrian taxa, are all consistent with, but not necessarily indicative of, a bilaterian affinity. A cataphract skeleton with an inferred complex microstructure confirms the presence of controlled biomineralization in metazoans by the terminal Ediacaran, and offers insights into the evolution of development and ecology at the root of the ‘Cambrian radiation’.
Exoskeletal dwelling tubes are widespread among extant animals and early fossil assemblages. Exceptional fossils from the Cambrian reveal independent origins of tube dwelling by several clades including cnidarians, lophophorates, annelids, scalidophorans, panarthropods and ambulacrarians. However, most fossil tubes lack preservation of soft parts, making it difficult to understand their affinities and evolutionary significance. Gangtoucunia aspera (Wulongqing Formation, Cambrian Stage 4) was an annulated, gradually expanding phosphatic tube, with occasional attachments of multiple, smaller juveniles and has previously been interpreted as the dwelling tube of a 'worm' (e.g. a scalidophoran), lophophorate or problematicum. Here, we report the first soft tissues from Gangtoucunia that reveal a smooth body with circumoral tentacles and a blind, spacious gut that is partitioned by septa. This is consistent with cnidarian polyps and phylogenetic analysis resolves Gangtoucunia as a total group medusozoan. The tube of Gangtoucunia is phenotypically similar to problematic annulated tubular fossils (e.g. Sphenothallus, Byronia, hyolithelminths), which have been compared to both cnidarians and annelids, and are among the oldest assemblages of skeletal fossils. The cnidarian characters of G. aspera suggest that these early tubular taxa are best interpreted as cnidarians rather than sessile bilaterians in the absence of contrary soft tissue evidence.
Cnidarians are a disparate and ancient phylum, encompassing corals and jellyfish, and occupy both the pelagic and benthic realms. They have a rich fossil record from the Phanerozoic eon lending insight into the early history of the group but, although cnidarians diverged from other animals in the Precambrian period, their record from the Ediacaran period (635–542 million years ago) is controversial. Here, we describe a new fossil cnidarian—Auroralumina attenboroughii gen. et sp. nov.—from the Ediacaran of Charnwood Forest (557–562 million years ago) that shows two bifurcating polyps enclosed in a rigid, polyhedral, organic skeleton with evidence of simple, densely packed tentacles. Auroralumina displays a suite of characters allying it to early medusozoans but shows others more typical of Anthozoa. Phylogenetic analyses recover Auroralumina as a stem-group medusozoan and, therefore, the oldest crown-group cnidarian. Auroralumina demonstrates both the establishment of the crown group of an animal phylum and the fixation of its body plan tens of millions of years before the Cambrian diversification of animal life. A new fossil cnidarian, Auroralumina attenboroughi, from the Ediacaran of Charnwood Forest, UK, described as showing mosaic anthozoan and medusozoan characters, is the oldest yet-known crown-group cnidarian.
Paraconularia ediacara n. sp., the oldest documented conulariid cnidarian, is described based on a compressed thin specimen from the terminal Ediacaran Tamengo Formation near Corumbá, Mato Grosso do Sul State, Brazil. The conulariid was collected from a laminated silty shale bed also containing Corumbella werneri and vendotaenid algae. The specimen consists of four partial faces, two of which are mostly covered, and one exposed corner sulcus. The two exposed faces exhibit 32 bell-curve-shaped, nodose transverse ribs, with some nodes preserving a short, adaperturally directed interspace ridge (spine). The transverse ribs bend adapertureward on the shoulders of the corner sulcus, within which the ribs terminate, with the end portions of the ribs from one face alternating with and slightly overlapping those from the adjoining face. This is the first Ediacaran body fossil showing compelling evidence of homology with a particular conulariid genus. However, unlike the periderm of Phanerozoic conulariids, the periderm of P. ediacara lacks calcium phosphate, a difference which may be original or an artifact of diagenesis or weathering. The discovery of P. ediacara in the Tamengo Formation corroborates the hypothesis, based in part on molecular clock studies, that cnidarians originated during mid-late Proterozoic times, and serves as a new internal calibration point, dating the split between scyphozoan and cubozoan cnidarians at no later than 542 Ma. Furthermore, P. ediacara reinforces the argument that the final phase of Ediacaran biotic evolution featured the advent of large-bodied eumetazoans, including, possibly, predators.
