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Aberrosquama occidens nov. gen. et sp. scales. A, GSWA F53618, crown view, holotype scale; B, GSWA F53630, crown view; C, D, GSWA F53631, base and lateral views; E, F, GSWA F53632, lateral and basal views; G, GSWA F53658, basal view; H, Vertical longitudinal section of scale GSWA F53684; I, GSWA F53636, scale with split or bipartite crown; J, K, GSWA F53633, basolateral view of tooth-like scale, with magnified view of base tissue. Scale bars ¼ 0.1 mm; A-G, I-K, SEMs; anterior of scales to right unless indicated by arrow.
Source publication
A core sample from the offshore Pendock 1A well, Carnarvon Basin, Western Australia yielded microvertebrate residues at an horizon in the lower part of the Hamelin Formation, dated as late Silurian, ? Ludlow, based on associated conodonts. The fish fauna comprises loganelliiform thelodont scales, the ? stem gnathostome Aberrosquama occidens nov. ge...
Contexts in source publication
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... monodontode. Description. Morphology. The scales are dark amber or black, with an opaque base and semi-translucent crown. Rounded edges and smooth surfaces indicate they could have been tumbled and abraded, but they are well preserved histologically. Scales are 0.3-0.45 mm long and 0.25-0.6 mm wide, and bear relatively smooth, subtriangular (Fig. 4B-D) or subrhombic tubercles, which usually slope upwards from anterior to posterior (Fig. 4D). Nearly all scales are monotuberculate/monodontode, resembling acanthodian scales morphologically. Scales mostly have a short 'neck' that is negligible anteriorly, deepening to the posterior, where it is in some cases overhung by the posterior ...
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... base and semi-translucent crown. Rounded edges and smooth surfaces indicate they could have been tumbled and abraded, but they are well preserved histologically. Scales are 0.3-0.45 mm long and 0.25-0.6 mm wide, and bear relatively smooth, subtriangular (Fig. 4B-D) or subrhombic tubercles, which usually slope upwards from anterior to posterior (Fig. 4D). Nearly all scales are monotuberculate/monodontode, resembling acanthodian scales morphologically. Scales mostly have a short 'neck' that is negligible anteriorly, deepening to the posterior, where it is in some cases overhung by the posterior point of the tubercle (Fig. 4A-G). Several large canal pores pierce the base (Fig. 4C-G) and ...
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... tubercles, which usually slope upwards from anterior to posterior (Fig. 4D). Nearly all scales are monotuberculate/monodontode, resembling acanthodian scales morphologically. Scales mostly have a short 'neck' that is negligible anteriorly, deepening to the posterior, where it is in some cases overhung by the posterior point of the tubercle (Fig. 4A-G). Several large canal pores pierce the base (Fig. 4C-G) and the outer surface of the base or neck around the crown odontode in some scales (Fig. 4A). The inclined planar surface of the crown is usually smooth and featureless (Fig. 4B); only the holotype scale also has an anterior, medial ridge and an oblique lateral ridge (Fig. ...
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... to posterior (Fig. 4D). Nearly all scales are monotuberculate/monodontode, resembling acanthodian scales morphologically. Scales mostly have a short 'neck' that is negligible anteriorly, deepening to the posterior, where it is in some cases overhung by the posterior point of the tubercle (Fig. 4A-G). Several large canal pores pierce the base (Fig. 4C-G) and the outer surface of the base or neck around the crown odontode in some scales (Fig. 4A). The inclined planar surface of the crown is usually smooth and featureless (Fig. 4B); only the holotype scale also has an anterior, medial ridge and an oblique lateral ridge (Fig. ...
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... scales morphologically. Scales mostly have a short 'neck' that is negligible anteriorly, deepening to the posterior, where it is in some cases overhung by the posterior point of the tubercle (Fig. 4A-G). Several large canal pores pierce the base (Fig. 4C-G) and the outer surface of the base or neck around the crown odontode in some scales (Fig. 4A). The inclined planar surface of the crown is usually smooth and featureless (Fig. 4B); only the holotype scale also has an anterior, medial ridge and an oblique lateral ridge (Fig. ...
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... deepening to the posterior, where it is in some cases overhung by the posterior point of the tubercle (Fig. 4A-G). Several large canal pores pierce the base (Fig. 4C-G) and the outer surface of the base or neck around the crown odontode in some scales (Fig. 4A). The inclined planar surface of the crown is usually smooth and featureless (Fig. 4B); only the holotype scale also has an anterior, medial ridge and an oblique lateral ridge (Fig. ...
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... the tubercle (Fig. 4A-G). Several large canal pores pierce the base (Fig. 4C-G) and the outer surface of the base or neck around the crown odontode in some scales (Fig. 4A). The inclined planar surface of the crown is usually smooth and featureless (Fig. 4B); only the holotype scale also has an anterior, medial ridge and an oblique lateral ridge (Fig. ...
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... sample includes two scales that each bear two tubercles (Fig. 4I), as well as a tooth-shaped element (Fig. 4J, K). The latter has a smooth crown with at least one large pore just above the rounded basal rim; the concave basal surface has a globular texture (Fig. ...
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... sample includes two scales that each bear two tubercles (Fig. 4I), as well as a tooth-shaped element (Fig. 4J, K). The latter has a smooth crown with at least one large pore just above the rounded basal rim; the concave basal surface has a globular texture (Fig. ...
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... sample includes two scales that each bear two tubercles (Fig. 4I), as well as a tooth-shaped element (Fig. 4J, K). The latter has a smooth crown with at least one large pore just above the rounded basal rim; the concave basal surface has a globular texture (Fig. ...
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... No superposed growth zones are recognized in the crown (Figs 4H, 5C, F, I), distinguishing them from classic acanthodian scales. The outer dentinous zone is a relatively clear nonbirefringent tissue, penetrated by fine tubules that are single, or have short branches coalescing into a single tubule, directed perpendicularly away from the outer surface (Fig. 5C, F, I). ...
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... MOTH locality in Canada. These Early Devonian MOTH taxa resemble acanthodians in having paired and median fin spines, but like Aberrosquama they have only monodontode scales. Unlike Aberrosquama scales, with their convex bone bases and complex fibre bundle complexes, scales of these two MOTH taxa lack a bony base. The simple tooth-like element (Fig. 4J, K), which has the large canal openings that characterize Aberrosquama scales, differs from any of the teeth known from other early ...
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