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A chancelloriid-like metazoan from the early Cambrian Chengjiang Lagerstätte, China.

Hou X, Williams M, Siveter DJ, Siveter DJ, Gabbott S, Holwell D, Harvey TH - Sci Rep (2014)

Bottom Line: Instead, the sac-like morphology invites comparison with the radially symmetrical chancelloriids.Alternatively, N. pugio may represent a group of radial metazoans that are discrete from chancelloriids.Whatever its precise phylogenetic position, N. pugio expands the known disparity of Cambrian scleritome-bearing animals, and provides a new model for reconstructing scleritomes from isolated microfossils.

View Article: PubMed Central - PubMed

Affiliation: Yunnan Key Laboratory for Palaeobiology, Yunnan University, Kunming 650091, China.

ABSTRACT
Nidelric pugio gen. et sp. nov. from the Cambrian Series 2 Heilinpu Formation, Chengjiang Lagerstätte, Yunnan Province, China, is an ovoid, sac-like metazoan that bears single-element spines on its surface. N. pugio shows no trace of a gut, coelom, anterior differentiation, appendages, or internal organs that would suggest a bilateral body plan. Instead, the sac-like morphology invites comparison with the radially symmetrical chancelloriids. However, the single-element spines of N. pugio are atypical of the complex multi-element spine rosettes borne by most chancelloriids and N. pugio may signal the ancestral chancelloriid state, in which the spines had not yet fused. Alternatively, N. pugio may represent a group of radial metazoans that are discrete from chancelloriids. Whatever its precise phylogenetic position, N. pugio expands the known disparity of Cambrian scleritome-bearing animals, and provides a new model for reconstructing scleritomes from isolated microfossils.

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High Resolution X-ray Computed Tomography 3D reconstructions of Nidelric pugio (YKLP11081a).(a), shows the surface of the specimen towards the broader end of the fossil (left) with areas containing Fe oxide-bearing material highlighted in green, with the highest density material (highest volume of Fe oxide) coloured yellow-green (centre), and a view with the less dense material stripped away to show just the highest density material that makes up the tips of the spines. Note the concentration of spines at this end of the fossil. (b), is a transverse view of the rock slab, with the sediment material stripped away. The grey areas represent parts of the material that contain some Fe-oxide and were identified as being higher density than the surrounding sediment. The highest density material is coloured red, which is where the amount of Fe-oxide is highest, and corresponds with the tips of the spines. The view is looking beneath the surface, and clearly demonstrates spines pointing down into the rock, interpreted as spines on the ‘lower' surface of YKLP11081a as preserved (see Fig. 1a–c, for spines that are clearly on the ‘upper' surface of YKLP11081a as preserved). Scale bars are indicated on the figure.
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f3: High Resolution X-ray Computed Tomography 3D reconstructions of Nidelric pugio (YKLP11081a).(a), shows the surface of the specimen towards the broader end of the fossil (left) with areas containing Fe oxide-bearing material highlighted in green, with the highest density material (highest volume of Fe oxide) coloured yellow-green (centre), and a view with the less dense material stripped away to show just the highest density material that makes up the tips of the spines. Note the concentration of spines at this end of the fossil. (b), is a transverse view of the rock slab, with the sediment material stripped away. The grey areas represent parts of the material that contain some Fe-oxide and were identified as being higher density than the surrounding sediment. The highest density material is coloured red, which is where the amount of Fe-oxide is highest, and corresponds with the tips of the spines. The view is looking beneath the surface, and clearly demonstrates spines pointing down into the rock, interpreted as spines on the ‘lower' surface of YKLP11081a as preserved (see Fig. 1a–c, for spines that are clearly on the ‘upper' surface of YKLP11081a as preserved). Scale bars are indicated on the figure.

Mentions: The body has a maximum width of 5.3 cm, and tapers to just over 1 cm at its narrowest point (Fig. 1a). It is ovoid and is preserved as a mosaic of red-grey patches interspersed with areas of lighter-coloured sediment that may represent degraded epithelial integument and internal soft tissues. In one place on the body, towards the broader end, there are a series of small, oval, probably interlocking structures, about 150 μm in maximum diameter, that probably represent the integument (Fig. 1e, g). No traces of internal organs are discerned. Single element spines are present at low-density over the whole surface of the animal, with the greatest concentration along the margins of the body, and at the broader end of the animal (Figs 1a–d, 2, 3a, b). The spines are elongate-triangular in profile and gradually tapering; they have variable preservation, mostly highlighted by iron oxide. These spines are typically 2.0 to 4.6 mm long, about 2.0 mm broad at their base, sharply pointed distally (Fig. 1b–d, f) and are preserved overlapping each other at the body margins (Fig. 1b–d), suggesting that they might have been concentrated into rows. At the broader end of the body, small and larger spines occur adjacent to each other, but generally the spines become smaller towards the narrower end of the body; many of the spines also point outwards in the direction of the narrow end of the body (Fig. 1a). The bases of some spines appear to be associated with a circular connection in the integument of the animal (Figs 1d, 2), but there is no evidence that the spines were embedded beneath the surface of the integument, and the exposed nature of the spines is clearly evident at the body margins (Fig. 1a–c). The margins and distal portions of the spines are covered with a sculpture of small triangular scales on at least one (upper or lower) surface (e.g. Fig. 1b–d, f), there being about 10–11 such scales across the maximum width of the spines. The medial proximal area of each spine is flat, relatively smooth, and apparently lacks scales.


A chancelloriid-like metazoan from the early Cambrian Chengjiang Lagerstätte, China.

Hou X, Williams M, Siveter DJ, Siveter DJ, Gabbott S, Holwell D, Harvey TH - Sci Rep (2014)

High Resolution X-ray Computed Tomography 3D reconstructions of Nidelric pugio (YKLP11081a).(a), shows the surface of the specimen towards the broader end of the fossil (left) with areas containing Fe oxide-bearing material highlighted in green, with the highest density material (highest volume of Fe oxide) coloured yellow-green (centre), and a view with the less dense material stripped away to show just the highest density material that makes up the tips of the spines. Note the concentration of spines at this end of the fossil. (b), is a transverse view of the rock slab, with the sediment material stripped away. The grey areas represent parts of the material that contain some Fe-oxide and were identified as being higher density than the surrounding sediment. The highest density material is coloured red, which is where the amount of Fe-oxide is highest, and corresponds with the tips of the spines. The view is looking beneath the surface, and clearly demonstrates spines pointing down into the rock, interpreted as spines on the ‘lower' surface of YKLP11081a as preserved (see Fig. 1a–c, for spines that are clearly on the ‘upper' surface of YKLP11081a as preserved). Scale bars are indicated on the figure.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4260403&req=5

f3: High Resolution X-ray Computed Tomography 3D reconstructions of Nidelric pugio (YKLP11081a).(a), shows the surface of the specimen towards the broader end of the fossil (left) with areas containing Fe oxide-bearing material highlighted in green, with the highest density material (highest volume of Fe oxide) coloured yellow-green (centre), and a view with the less dense material stripped away to show just the highest density material that makes up the tips of the spines. Note the concentration of spines at this end of the fossil. (b), is a transverse view of the rock slab, with the sediment material stripped away. The grey areas represent parts of the material that contain some Fe-oxide and were identified as being higher density than the surrounding sediment. The highest density material is coloured red, which is where the amount of Fe-oxide is highest, and corresponds with the tips of the spines. The view is looking beneath the surface, and clearly demonstrates spines pointing down into the rock, interpreted as spines on the ‘lower' surface of YKLP11081a as preserved (see Fig. 1a–c, for spines that are clearly on the ‘upper' surface of YKLP11081a as preserved). Scale bars are indicated on the figure.
Mentions: The body has a maximum width of 5.3 cm, and tapers to just over 1 cm at its narrowest point (Fig. 1a). It is ovoid and is preserved as a mosaic of red-grey patches interspersed with areas of lighter-coloured sediment that may represent degraded epithelial integument and internal soft tissues. In one place on the body, towards the broader end, there are a series of small, oval, probably interlocking structures, about 150 μm in maximum diameter, that probably represent the integument (Fig. 1e, g). No traces of internal organs are discerned. Single element spines are present at low-density over the whole surface of the animal, with the greatest concentration along the margins of the body, and at the broader end of the animal (Figs 1a–d, 2, 3a, b). The spines are elongate-triangular in profile and gradually tapering; they have variable preservation, mostly highlighted by iron oxide. These spines are typically 2.0 to 4.6 mm long, about 2.0 mm broad at their base, sharply pointed distally (Fig. 1b–d, f) and are preserved overlapping each other at the body margins (Fig. 1b–d), suggesting that they might have been concentrated into rows. At the broader end of the body, small and larger spines occur adjacent to each other, but generally the spines become smaller towards the narrower end of the body; many of the spines also point outwards in the direction of the narrow end of the body (Fig. 1a). The bases of some spines appear to be associated with a circular connection in the integument of the animal (Figs 1d, 2), but there is no evidence that the spines were embedded beneath the surface of the integument, and the exposed nature of the spines is clearly evident at the body margins (Fig. 1a–c). The margins and distal portions of the spines are covered with a sculpture of small triangular scales on at least one (upper or lower) surface (e.g. Fig. 1b–d, f), there being about 10–11 such scales across the maximum width of the spines. The medial proximal area of each spine is flat, relatively smooth, and apparently lacks scales.

Bottom Line: Instead, the sac-like morphology invites comparison with the radially symmetrical chancelloriids.Alternatively, N. pugio may represent a group of radial metazoans that are discrete from chancelloriids.Whatever its precise phylogenetic position, N. pugio expands the known disparity of Cambrian scleritome-bearing animals, and provides a new model for reconstructing scleritomes from isolated microfossils.

View Article: PubMed Central - PubMed

Affiliation: Yunnan Key Laboratory for Palaeobiology, Yunnan University, Kunming 650091, China.

ABSTRACT
Nidelric pugio gen. et sp. nov. from the Cambrian Series 2 Heilinpu Formation, Chengjiang Lagerstätte, Yunnan Province, China, is an ovoid, sac-like metazoan that bears single-element spines on its surface. N. pugio shows no trace of a gut, coelom, anterior differentiation, appendages, or internal organs that would suggest a bilateral body plan. Instead, the sac-like morphology invites comparison with the radially symmetrical chancelloriids. However, the single-element spines of N. pugio are atypical of the complex multi-element spine rosettes borne by most chancelloriids and N. pugio may signal the ancestral chancelloriid state, in which the spines had not yet fused. Alternatively, N. pugio may represent a group of radial metazoans that are discrete from chancelloriids. Whatever its precise phylogenetic position, N. pugio expands the known disparity of Cambrian scleritome-bearing animals, and provides a new model for reconstructing scleritomes from isolated microfossils.

Show MeSH