Pterodactylus scolopaciceps Meyer, 1860 (Pterosauria, Pterodactyloidea) from the Upper Jurassic of Bavaria, Germany: the problem of cryptic pterosaur taxa in early ontogeny - PubMed (original) (raw)

Pterodactylus scolopaciceps Meyer, 1860 (Pterosauria, Pterodactyloidea) from the Upper Jurassic of Bavaria, Germany: the problem of cryptic pterosaur taxa in early ontogeny

Steven U Vidovic et al. PLoS One. 2014.

Erratum in

Abstract

The taxonomy of the Late Jurassic pterodactyloid pterosaur Pterodactylus scolopaciceps Meyer, 1860 from the Solnhofen Limestone Formation of Bavaria, Germany is reviewed. Its nomenclatural history is long and complex, having been synonymised with both P. kochi (Wagner, 1837), and P. antiquus (Sömmerring, 1812). The majority of pterosaur species from the Solnhofen Limestone, including P. scolopaciceps are represented by juveniles. Consequently, specimens can appear remarkably similar due to juvenile characteristics detracting from taxonomic differences that are exaggerated in later ontogeny. Previous morphological and morphometric analyses have failed to separate species or even genera due to this problem, and as a result many species have been subsumed into a single taxon. A hypodigm for P. scolopaciceps, comprising of the holotype (BSP AS V 29 a/b) and material Broili referred to the taxon is described. P. scolopaciceps is found to be a valid taxon, but placement within Pterodactylus is inappropriate. Consequently, the new genus Aerodactylus is erected to accommodate it. Aerodactylus can be diagnosed on account of a unique suite of characters including jaws containing 16 teeth per-jaw, per-side, which are more sparsely distributed caudally and terminate rostral to the nasoantorbital fenestra; dorsal surface of the skull is subtly depressed rostral of the cranial table; rostrum very elongate (RI = ∼7), terminating in a point; orbits correspondingly low and elongate; elongate cervical vertebrae (approximately three times the length of their width); wing-metacarpal elongate, but still shorter than the ulna and first wing-phalanx; and pteroid approximately 65% of the total length of the ulna, straight and extremely thin (less than one third the width of the ulna). A cladistic analysis demonstrates that Aerodactylus is distinct from Pterodactylus, but close to Cycnorhamphus Seeley, 1870, Ardeadactylus Bennett, 2013a and Aurorazhdarcho Frey, Meyer and Tischlinger, 2011, consequently we erect the inclusive taxon Aurorazhdarchidae for their reception.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1

Figure 1. The part and counterpart of Pterodactylus scolopaciceps (BSP AS V 29 a [right] b [left]) holotype.

Scale bar = 20 mm.

Figure 2

Figure 2. Pterodactylus specimens with soft tissue.

A) Broili (1938) specimen of Pterodactylus scolopaciceps (BSP 1937 I 18) demonstrating extensive soft tissue (scale bar = 20 mm); B) soft tissue occipital head crest from a “_Pterodactylus kochi_” specimen (BSP 1883 XVI 1); i) photograph; ii) line drawing (scale bar = 20 mm).

Figure 3

Figure 3. Line drawings of seven skulls belonging to Pterodactylus antiquus (sensu Bennett [2]).

A & B) two opposing reconstructions of the holotype of P. kochi (SMF R 404/BSP AS XIX); C) the holotype of Pterodactylus antiquus (BSP AS I 739); D) a large specimen of “_Pterodactylus kochi_” (BSP 1883 XVI 1); E) Broili (1938) specimen of Pterodactylus scolopaciceps (BSP 1937 I 18); F) the holotype of Pterodactylus scolopaciceps (BSP AS V 29 a/b); G) a small juvenile specimen of Pterodactylus kochi (NHMUK PV R 3949, OUMNH JZ 1609); H) a small juvenile specimen of Pterodactylus kochi (SMF R 4072). Scale bars = 10 mm.

Figure 4

Figure 4. A graph of Solnhofen pterodactyloids compiled from data available in Wellnhofer .

Skull length plotted along the x-axis, wing metacarpal length plotted along the y-axis. Despite clear morphological differences a crowded data set has resulted in all specimens appearing similar. A similar situation is observed when all other elements plotted against skull length. P. antiquus filled circles, P. kochi open squares, Ctenochasma open circles. R2 values: all specimens = 0.931; P. antiquus specimens = 0.998; P. kochi specimens = 0.959; Ctenochasma gracile + P. elegans ( = Ctenochasma elegans) = 0.942. Dashed lines are regression lines for each respective taxon, the solid line is the regression line for all specimens.

Figure 5

Figure 5. A demonstration of i = tan−1a/b rescaling on triangles with opposing dimensions.

The plots at the top demonstrate the data distribution of the triangles illustrated below, where Q = raw quotient value of triangle length/depth, and i = rescaled quotient values of triangle length/depth. The colours of triangles Ai – Ci, Aii – Cii and D are replicated in the diamonds in the plots for clarity. The depths (di) of Ai – Ci are equal to the lengths (also di) of Aii – Cii respectively. Likewise, the lengths (dii) of Ai – Ci are equal to the depths (also dii) of Aii – Cii. D is an equilateral triangle, and on the plots it demonstrates the transition between tall and long forms. The diagram demonstrates that triangles with the same range of variation between both shallow-long forms and deep-short forms will only exhibit the true range of variation once the i = tan−1a/b rescaling has been applied.

Figure 6

Figure 6. A single most parsimonious tree of the Pterodactyloidea recovered using a TNT “new technology search”.

Named nodes: 1 = Monofenestrata Lü et al. 2010 ; 2 = Pterodactyloidea Plieninger 1901 ; 3 = Ctenochasmatidae Nopcsa 1928 ; 4 = Lophocratia Unwin 2003 ; 5 = Aurorazhdarchidae fam. nov.; 6 = Ornithocheiroidea Seeley 1891 ; 7 = Istiodactylidae Howse et al. 2001 ; 8 = Pteranodontia Marsh 1876 ; 9 = Anhangueridae Campos and Kellner 1985 ; 10 = Tapejaroidea Kellner 1996 ; 11 = Azhdarchoidea Nesov 1984 ; 12 = Azhdarchidae Nesov 1984 ; 13 = Tapejaridae Kellner 1989 .

Figure 7

Figure 7. Skull length vs skull depth.

A graph demonstrating the spread of data between morphotype one (open circles), morphotype two (filled circles) and Pterodactylus antiquus (Open square) in respect to their skull length and skull depth. Solid black lines = regression lines for respective morphotypes; dashed grey lines = 95% confidence limits.

Figure 8

Figure 8. Skull depth vs cervical vertebra 5 length.

A graph demonstrating the spread of data between morphotype one (open circles), morphotype two (filled circles) and Pterodactylus antiquus (Open square) in respect to their skull depth and cervical vertebra 5 length. Solid black lines = regression lines for respective morphotypes; dashed grey lines = 95% confidence limits.

Figure 9

Figure 9. Orbit depth vs femur length.

A graph demonstrating the spread of data between morphotype one (open circles), morphotype two (filled circles) and Pterodactylus antiquus (Open square) in respect to their orbit depth and femur length. Solid black lines = regression lines for respective morphotypes; dashed grey lines = 95% confidence limits.

Figure 10

Figure 10. Nasoantorbital fenestra length vs nasoantorbital fenestra depth.

A graph analysing the relationships of nasoantorbital fenestra length and depth dimensions, which demonstrates intersecting regression lines for morphotype one (open circles) and morphotype two (filled circles), Pterodactylus antiquus (open square) lies closest to morphotype two. Solid black lines = regression lines for respective morphotypes; dashed grey lines = 95% confidence limits.

Figure 11

Figure 11. Skull depth vs PCRW.

A graph demonstrating the spread of data between morphotype one (open circles), morphotype two (filled circles) and Pterodactylus antiquus (open square) in respect to their skull depth and the length of their PCRW. Solid black lines = regression lines for respective morphotypes; dashed grey lines = 95% confidence limits.

Figure 12

Figure 12. Absolute frequencies of R2 values from the extensive graphical analyses.

A line graph demonstrating the frequencies (y-axis) of R2 values for each respective hypothesis tested in the 120 graphs. The R2 values are ordered from strong support to low support, left to right (x-axis). Morphotype one is represented by a dashed line, morphotype two is represented by a solid line, all specimens of “_Pterodactylus_” are represented by a dotted line. The highest peaks of the two morphotypes are marked and labelled. The area under the strongest supported hypothesis (morphotype two) is shaded grey for clarity. Likewise, the topologies of the lines are reproduced to the right of the graph.

Figure 13

Figure 13. A demonstration of the breadth of the quadratojugal’s rostral portion.

A) Pterodactyulus antiquus; B) Cycnorhamphus suevicus; C) Aerodactylus scolopaciceps. j, jugal; q, quadrate; qj, quadratojugal. Scale bars = 10 mm.

Figure 14

Figure 14. Cladograms based on the results of a cladistic analysis by Howse .

Pterodactylus elegans = Ctenochasma elegans; Pterodactylus micronyx = Aurorazhdarcho micronyx; Gallodactylus = Cycnorhamphus; Pterodactylus longicollum = Ardeadactylus longicollum; Doratorhynchus = Pterodactyloidea incertae sedis. (?azhdarchid?); Titanopteryx = Arambourgiana; Greensand long cervical vertebrae = no specimen number or reference given.

Figure 15

Figure 15. A private specimen of Aerodactylus demonstrating the shoulder girdle morphology.

A) A photograph of a private specimen, which plots onto all graphs on the regression line belonging to morphotype two, thus is identified as Aerodactylus scolopaciceps gen. nov. The area of the photograph illustrates the morphology of the coracoid and humerus. The humerus is more similar to that of Aurorazhdarcho, but the proportions of the wing metacarpal are similar to Aerodactylus scolopaciceps gen. nov. B) Interpretive line diagram: co, coracoid; cv, cervical vertebra; hu, humerus; pt, pteroid; ra, radius; sc, scapula; ul, ulna; wph1, wing-phalanx one; wph2, wing-phalanx two. Scale bar = 10 mm.

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Grants and funding

SUV received a small grant to visit the natural history museum in Basel, in aid of this project. The funding was provided by the Systematics Association and Linnean Society, London, through the “Systematics Research Fund” http://www.systass.org/awards/srf11-12results.shtml. No funds were provided for publication costs. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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