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FIG. 7. — Specimen MPV 2020.1.2 in New data on the theropod diversity from the Middle to Late Jurassic of the Vaches Noires cliffs (Normandy, France)

FIG. 7. — Specimen MPV 2020.1.2, proximal end of left tibia of?Streptospondylus altdorfensis from Callovian or Oxfordian marls, in anterior (A), medial (B), proximal (C), lateral (D), posterior (E) views. Abbreviations: cnc, cnemial crest; fc, fibular crest; ict, incisura tibialis. Scale bar: 5 cm.

FIG. 3. — Specimen MNHN.F.RJN471 in New data on the theropod diversity from the Middle to Late Jurassic of the Vaches Noires cliffs (Normandy, France)

FIG. 3. — Specimen MNHN.F.RJN471, right femur of an indeterminate Megalosauridae from H14 level of Marnes de Villers, in anterior (A) and lateral (B) views; proximal end in proximal view (C); distal end in proximal (D), medial (E) and distal (F) views. Abbreviations: eg, extensor groove; gt, great trochanter; lc, lateral condyle; lt, lesser trochanter; mc, medial condyle; mdc, mesiodistal crest. Scale bar: 10 cm.

FIG. 6 in New data on the theropod diversity from the Middle to Late Jurassic of the Vaches Noires cliffs (Normandy, France)

FIG. 6. — Dorsal vertebrae of Streptospondylus altdorfensis from Vaches Noires cliffs. Specimen MNHN.F.RJN82 of the type specimen of Streptospondylus altdorfensis in right lateral (A) and ventral (B) views. Specimen MPV 2020.1.10 (Callovian or Oxfordian marls) in right lateral (C) and ventral (D) views. Specimen B5 (Oolithes Ferrugineuse de Villers), in right lateral (E) and ventral (F) views. Abbreviations:ddpc, double pleurocentral depression; vp, ventral plateau.Scale bars:5 cm.

FIG. 4 in New data on the theropod diversity from the Middle to Late Jurassic of the Vaches Noires cliffs (Normandy, France)

FIG. 4. —?Streptospondylus altdorfensis, anterior cervical vertebra (MPV 2020.1.11), Oxfordian marls, in anterior (A), posterior (B) and right lateral (C) views. Abbreviations: ags, Actinostreon gregareum shell; cpol, centropostzygapophyseal lamina; cprf, centroprezygapophyseal fossa; dp, diapophysis; ns, neural spine; plr, pleurocoele; podl, postzygodiapophyseal lamina; pp, parapophysis; pr, prezygapophysis; spof, spinopostzygodiapophyseal fossa; sprf, spinoprezygapohyseal fossa. Scale bar: 5 cm.

FIG. 1 in New data on the theropod diversity from the Middle to Late Jurassic of the Vaches Noires cliffs (Normandy, France)

FIG. 1. — Vaches Noires cliffs synthetic log with studied specimen position. Grey interval indicates unclear provenance; dotted line is for easily recognizable Oolithes Ferrugineuse de Villers (modified from Dugué et al. 1998).

FIG. 2 in New data on the theropod diversity from the Middle to Late Jurassic of the Vaches Noires cliffs (Normandy, France)

FIG. 2. — Megalosauroidea indet., left premaxilla (B1), Oolithes Ferrugineuses de Villers, in lateral (A), medial (B) and posterior (C) views. Distal denticles of a replacement tooth of the first alveoli in lingual view (D). Abbreviations: snf, subnarial foramen. Scale bars: A-C, 5 cm; D, 1 mm.

FIG. 5. — Specimen MNHN.F.RJN472 in New data on the theropod diversity from the Middle to Late Jurassic of the Vaches Noires cliffs (Normandy, France)

FIG. 5. — Specimen MNHN.F.RJN472, anterior dorsal vertebra of Streptospondylus altdorfensis from Oolithes Ferrugineuse de Villers, in left lateral (A), posterior (B), dorsal (C) and ventral (D) views. Abbreviations: pcd, pleurocentral depression; pp, parapophysis; vp, ventral plateau. Scale bar: 5 cm.

opencc-zeroNov 2019View details →

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Data from: Comparative crystallography suggests Maniraptoran theropod affinities for latest cretaceous European 'geckoid' eggshell

Thin fossil eggshells from Upper Cretaceous deposits of Europe, characterized by nodular ornamentation similar to modern gekkotan eggshells, have mostly been interpreted as gekkotan (='geckoid') in origin. However, in some cases, like the oogenus Pseudogeckoolithus, their theropod affinity was also suggested. The true affinity of these fossil 'geckoid' eggshells remained controversial due to the absence of analytical methods effective in identifying genuine gecko eggshells in the fossil record. In this study, we apply electron backscatter diffraction (EBSD) analysis to latest Cretaceous European 'geckoid' (including Pseudogeckoolithus) eggshells, in comparison with modern gekkotan and theropod (avian) eggshells. Our results show that Pseudogeckoolithus has a definite theropod eggshell-like crystallographic configuration, in clear contrast to that seen in modern geckos. Furthermore, the crystallography of the nodular ornamentation in Pseudogeckoolithus is comparable to that seen in megapode eggshells, but different from that of gecko eggshells, despite superficial morphological similarity. The remarkable morphological similarities between Pseudogeckoolithus and modern gecko eggshells are thus convergent, and the 'gekkotan affinity' hypothesis can be dismissed for Pseudogeckoolithus. This study provides a template for differentiating true gekkotan from dinosaurian eggshells in the fossil record. The potential functional significance of eggshell ornamentation, lost in most modern birds, requires further study, and experimental zoological approach may shed light on this issue. Finally, our results caution about the dangers of using potentially homoplastic eggshell characters in eggshell parataxonomy.

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New giant carnivorous dinosaur reveals convergent evolutionary trends in theropod arm reduction

Giant carnivorous dinosaurs such as Tyrannosaurus rex and abelisaurids are characterized by highly reduced forelimbs that stand in contrast to their huge dimensions, massive skulls, and obligate bipedalism. Another group that follows this pattern, yet is still poorly known, is the Carcharodontosauridae: dominant predators that inhabited most continents during the Early Cretaceous and reached their largest sizes in Aptian-Cenomanian times. Despite many discoveries over the last three decades, aspects of their anatomy, especially with regard to the skull, forearm, and feet, remain poorly known. Here we report a new carcharodontosaurid, Meraxes gigas, gen. et sp. nov., based on a specimen recovered from the Upper Cretaceous Huincul Formation of northern Patagonia, Argentina. Phylogenetic analysis places Meraxes among derived Carcharodontosauridae, in a clade with other massive South American species. Meraxes preserves novel anatomical information for derived carcharodontosaurids, including an almost complete forelimb that provides evidence for convergent allometric trends in forelimb reduction among three lineages of large-bodied, megapredatory non-avian theropods, including a remarkable degree of parallelism between the latest-diverging tyrannosaurids and carcharodontosaurids. This trend, coupled with a likely lower bound on forelimb reduction, hypothesized to be about 0.4 forelimb/femur length, combined to produce this short-armed pattern in theropods. The almost complete cranium of Meraxes permits new estimates of skull length in Giganotosaurus, which is among the longest for theropods. Meraxes also provides further evidence that carchardontosaurids reached peak diversity shortly before their extinction with high rates of trait evolution in facial ornamentation possibly linked to a social signaling role.

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Fig. 4 in The Jordan theropod (Maastrichtian, Montana, U.S.A.) referred to the genus Aublysodon

Fig. 4 - Comparison of The skulls of A, Aubtysodon; B, Coelopbysis (AMNB 7224); C, Dromaeosaurus (modified from Coibert & Russell, 1969, Fig. 1); D, Velociraptor (modified from Barsbold, 1982, Fig. la); E, Sauromitboides (modified from Barsbold, 1974, Pl. 1), V, Dromiceiomimus (modified from Russell, 1972, Fig. 5, and ROM 840); G, Caegnatbus (modified from Sternberg, 1949, Fig. 1, and Barsbold, 1982, Fig. c); H, Albeltosaurus libratus (modified from Gilmore, 1946, Pl. 4, Fig. 3); I, Daspletosaurus torosus (modified from Russell, 1970, Fig. 6); J, "Albertosaurus" lancensis (modified from Gilmore, 1946, Pl. 1); H, Tyrannosaurus (modified from Osborn, 1912, Fig. 1); L, lingual (top) and labial (bottom) views of the dentaries of "Cbirostenotes" (modified from Gilmore, 1924, Fig. 3). Scale bar represents 10 cm. Comparaison des cranes des divers théropodes: A, Aubtysodon; B, Coelopbysis (AMNB 7224); C, Dromaeosaurus (modifiés d'après Colbert & Russell 1969, Fig. 1); D, Velociraptor (modifié d'après Barsbold 1982, Fig. la); E, Sauromitboides (modifié d'après Barsbold 1974, Pl. 1); F, Dromiceiomimus (modifié d'après Russell 1972, Fig. 5 et ROM 840); C, Caenagnatbus (modifié d'après Sternberg 1949, Fig. 1 et Barsbold 1982, Fig. c); H, Albertosaurus libratus (modifié d'après Gilmore 1946, PI. 4, Fig. 3); I, Daspletosaurus torosus (modifié d'après Russell 1970, Fig. 6);J, "Albertosaurud' lancensis (modifié d'après Gilmore 1946, Pl. 1); K, Tyrannosaurus (modifié d'après Osborn 1912, Fig. 1); L, les vues linguale (en haut) et labiale (en bas) des dentaires du "Cbirostenotes" (modifié d'après Gilmore 1924, Fig. 3). Echelle = 10 cm.

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Fig. 2 in The Jordan theropod (Maastrichtian, Montana, U.S.A.) referred to the genus Aublysodon

Fig. 2 - Cheek teeth of Aubtysodon mirandus. Left sixth maxillary tooth, as preserved, in lateral (A) and posterior (B) aspects. Right fourth dentary tooth, rendered in unworn condition, in anterior (C) and labial (D) aspects. Scale bar represents 10 mm. Les dents jugales de VAubtysodon mirandus. Sixième dent maxiliaire gauche telle qu'elle est conservée en vue laterale (A) et vue postérieure (B). Quatrième dent du dentaire droit, figurées sans usure en vue antérieure (C) et en vue labiale (D). Echelle: 10 mm.

Fig. 4 in Iridescent plumage in a juvenile dromaeosaurid theropod dinosaur

Fig. 4. Reconstruction of the dromaeosaurid dinosaur Wulong bohaiensis Poust, Gao, Varricchio, Wu, and Zhang, 2020 (DNHM D2933), from Shangheshou, Chaoyang, Liaoning, China, Early Cretaceous Jiufotang Formation with a minimum age of 120.3 Ma. This illustration broadly depicts iridescent plumage on the limbs and grey feathers on the body. It should be noted that the full extent of the iridescence has been extrapolated in the creation of this illustration, based on the evidence provided by a small but significant distribution of iridescent samples across several limbs of the fossil. Artwork by Robert Nicholls (Bob Nicholls Art).

Fig. 2 in Iridescent plumage in a juvenile dromaeosaurid theropod dinosaur

Fig. 2. Preserved melanosome imprints characteristic of each sample from the dromaeosaurid dinosaur Wulong bohaiensis Poust, Gao, Varricchio, Wu, and Zhang, 2020 (DNHM D9233) from Shangheshou, Chaoyang, Liaoning, China, Early Cretaceous Jiufotang Formation with a minimum age of 120.3 Ma. All melanosome imprints are from solid and cylindrical melanosomes. Preservation on samples 7 and 14 is less clear. Three distinctive types of melanosome morphology were found on sample 15. Each was measured separately and treated as different samples for analysis (15a/15b/15c).

Fig. 3 in Iridescent plumage in a juvenile dromaeosaurid theropod dinosaur

Fig. 3. Melanosome length against diameter for each colour category. The fifth panel shows the measurements for the dromaeosaurid dinosaur Wulong bohaiensis Poust, Gao, Varricchio, Wu, and Zhang, 2020 (DNHM D2933), from Shangheshou, Chaoyang, Liaoning, China, Early Cretaceous Jiufotang Formation with a minimum age of 120.3 Ma. Note 15c, which outlies all extant measurements. This figure is a good visual representation of why the models conflict in their prediction for 15c. cluded in SOM: table S2. Sample 15 is from the chest region Colour prediction.—In this study, the two prevailing preof the abdomen. Multiple unique populations of melano- dictive modelling approaches (QDA and MLR) for analysing somes were observed with differing morphologies. These fossil melanosome shape were applied to each of the datawere treated as separate samples (15a, 15b, and 15c) and sets (see Table 1), using length, diameter and aspect ratio as assessed for their colour. Fig. 3 plots length against diam- predictor variables for the QDA. For MLR, diameter, aspect eter for the melanosome data, with the right-most panel in- ratio, hollowness (categorical) and flatness (categorical) precluding the measurements from Wulong bohaiensis DNHM dictor variables were used. The analyses were conducted in D2933 facilitating visual comparison of the colour category Stata-16 (StataCorp 2019a), see SOM for commands to exedistributions in the first four panels. cute the models and justifications for the variable selection. Accounting for melanosome shrinkage.—Only melanosome The first dataset "LiNord" incorporates the Nordén et al. imprints were available for study, which have been argued (2019) modifications of the original Li et al. (2012) dataset to preserve the original morphology better than organically where, to avoid systematic bias from different sampling preserved melanosomes (Vinther 2020). Organically pre- methods and sample sizes, coefficient of variation and skew served melanosomes appear to shrink isometrically up to variables were excluded, as well as all samples with a sam- ~20% (McNamara et al. 2013; Colleary et al. 2015). The ple size less than 10. It does not include any of the new addiassumption is that if the rock matrix formed earlier than the tional samples from Hu et al. (2018) or Nordén et al. (2019). diagenetic shrinkage taking place, then imprints are a better The second dataset "NordSC" is a revised version of the proxy for the original size. While aspect ratio is unaffected expanded Nordén et al. (2019) dataset. First, a minor correcby shrinkage, the length and diameter would be affected tion reassigned colour categories to four samples that were and could affect predictions. To inspect this effect, three mislabelled (see SOM). Nordén et al. (2019) also excluded the scaling compensations of 10%, 20%, and 30% for length species sampled by Hu et al. (2018) because the data was not and diameter have been applied to investigate any possible phylogenetically broad, instead creating their own, broader shift in prediction. iridescent dataset. Additionally, here all hollow and flat sam-

Fig. 5 in Iridescent plumage in a juvenile dromaeosaurid theropod dinosaur

Fig. 5. Variation of probability with respect to the aspect ratio predictor variable (one of the two variables included in analysis M2). This plot shows that at aspect ratios of approximately 2.5–3.5, the probabilities of predicting any of the four possible colour categories are similar, and none are very likely. Several samples in Wulong bohaiensis (DNHM D2933) had an aspect ratio within this range.

Fig. 1 in Iridescent plumage in a juvenile dromaeosaurid theropod dinosaur

Fig. 1. Dromaeosaurid dinosaur Wulong bohaiensis Poust, Gao, Varricchio, Wu, and Zhang, 2020 (DNHM D2933), from Shangheshou, Chaoyang, Liaoning, China, Early Cretaceous Jiufotang Formation with a minimum age of 120.3 Ma (A1). Samples 1–16 were labelled by SLB while taking samples at the museum. Illustration by JV (A2) to show distinct plumage groupings on Wulong bohaiensis (DNHM D2933). For clarity, in this illustration only the samples with successful melanosome preservation are labelled. Preservation on each of the excluded samples was not sufficient for study.

Fig. 6 in Allometric growth in the frontals of the Mongolian theropod dinosaur Tarbosaurus bataar

Fig. 6. Björk method of superimposition of the frontals in dorsal/ventral views. A. Scaled to same length between prefrontonasal process and the frontoparietal suture. B. Smallest and largest specimen superimposed. C. Smallest and second largest specimen superimposed. D. Scaled to same width between medial edge of the orbital slot and the midline. E. Smallest and largest specimen superimposed. F. Smallest and second largest specimen superimposed. Largest specimens preserve entire nasal process, which emphasize relative shortening during growth. Not to scale.

Fig. 7 in Allometric growth in the frontals of the Mongolian theropod dinosaur Tarbosaurus bataar

Fig. 7. Björk method of superimposition of the frontals in lateral/medial views. A. Scaled to same length between prefrontonasal process and the frontoparietal suture. B. Smallest and largest specimen superimposed. C. Scaled to same depth near the lacrimal socket region. D. Smallest and largest specimen superimposed. Largest specimens preserve entire nasal process, which emphasize relative shortening during growth. Not to scale.

Fig. 5 in Allometric growth in the frontals of the Mongolian theropod dinosaur Tarbosaurus bataar

Fig. 5. Bivariate allometric results of different parts of Tarbosaurus bataar frontals. A. Length of the frontal between prefrontonasal process and the frontoparietal suture (pfn-pl length, 4) and the length of the postorbital suture (ps length, 10). B. Length of the frontal between prefrontonasal process and the frontoparietal suture (4) and the depth of the anterior part of the postorbital suture (rps depth, 11). C. Length of the frontal between prefrontonasal process and the frontoparietal suture (4) and the depth of the posterior part of the postorbital suture (cps depth, 12). D. Depth of the anterior part of the postorbital suture (11) and the depth of the posterior part of the postorbital suture (12). E. Depth of the frontal at the region that is immediately anterior to the most anterior point of the sagittal crest (depth, 9) and the depth of the anterior part of the postorbital suture (11). F. Depth of the frontal at the region that is immediately anterior to the most anterior point of the sagittal crest (9) and the depth of the posterior part of the postorbital suture (12). G. Length of the frontal between prefrontonasal process and the frontoparietal suture (4) and the length of the dorsotemporal fossa (dtf length, 7). H. Width of the frontal between medial edge of the orbital slot and the midline (os-mid width, 5) and the length of the dorsotemporal fossa (7).

Fig. 1. Tyrannosaurid theropod Tarbosaurus bataar Maleev, 1955a in Allometric growth in the frontals of the Mongolian theropod dinosaur Tarbosaurus bataar

Fig. 1. Tyrannosaurid theropod Tarbosaurus bataar Maleev, 1955a from Mongolia, Nemegt Formation, Maastrichtian; frontals used to create bone silhouettes for superimposition. A. MPC-D 107/10, from Bugiin Tsav, in dorsal (A1) and lateral (A2) views. B. MPC-D 107/09, Bugiin Tsav, in dorsal (B1) and lateral (B2) views. C. MPC-D 107/05, Nemegt, in dorsal view. D. MPC-D 107/11, Bugiin Tsav, in dorsal view. E. MPC-D 107/13, Nemegt, in dorsal (E1) and lateral (E2) views. F. MPC-D 107/22, Bugiin Tsav, in dorsal (F1) and lateral (F2) views. G. MPC-D 107/06, Bugiin Tsav, in dorsal (G1) and medial (G2) views. The arrangement is from smallest to largest. Scale bars 50 mm.