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Skin impressions from the dorsal part of the body showing a rosette. Preserved as a natural mold. Scale bar 1 cm
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Dinosaur skin impressions are rare in the Upper Jurassic Morrison Formation, but different sites on the Howe Ranch in Wyoming (USA), comprising specimens from diplodocid, camarasaurid, allosaurid and stegosaurian dinosaurs, have proven to be a treasure-trove for these soft-tissue remains. Here we describe stegosaurian skin impressions from North Am...
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... much rarer and larger second type of scale is present towards the dorsal side of the animal. These are higher, domed, five to ten times larger than the small scales, and ellipsoid in outline (Fig. 5). Each of them is surrounded by 9-13 small tubercles, which are not distinguishable from the scales forming the ground pattern. Only two such structures can be confidently identified, and thus a specific arrangement of these is therefore not discernable. The larger of the two scales is 20 9 15 mm, whereas the other ...
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The Uinta Mountains of northeastern Utah preserve the northernmost outcrops of classic early Mesozoic stratigraphic units on the Colorado Plateau, and document the transition to equivalent strata further north in Wyoming. In this region, the predominantly fluvial Upper Triassic Chinle Formation is overlain by the predominantly eolian Upper Triassic...
The plated thyreophoran or stegosaurian dinosaur Stegosaurus
armatus was named in 1877 by Marsh for fragmentary remains from the Morrison Formation (Upper Jurassic) of Colorado, USA. Subsequent discoveries from the same formation in Wyoming and Colorado (USA) have been assigned to separate stegosaurian genera and species, but most of these are no l...
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Background
Macelognathus vagans Marsh, 1884 from the Late Jurassic Morrison Fm. of Wyoming was originally described as a dinosaur by Marsh and in 1971 Ostrom suggested crocodilian affinities. In 2005, Göhlich and collaborators identified new material of this species from Colorado as a basal crocodylomorph. However, a partial skull found in associat...
Citations
... The non-polarised and non-overlapping tuberculate scales of most theropods are also found in the large majority of sauropodomorphs and ornithischians (e.g. Czerkas, 1994;Coria & Chiappe, 2007;Christiansen & Tschopp, 2010;Arbour et al., 2013;Godefroit et al., 2020;Gallagher, Poole & Schein, 2021). In modern reptiles, these scales are particularly present on the heads of snakes and lizards, and as isolated scales on the flanks of the green iguana Iguana iguana (Chang et al., 2009). ...
... Psittacosaurus, Chasmosaurus, Centrosaurus (Brown, 1917;Sternberg, 1925;Lingham-Soliar & Plodowski, 2010)], hadrosaurid [e.g. Edmontosaurus, Gryposaurus, Maiasaura, Saurolophus (Bell, 2012], and stegosaurid [Hesperosaurus, Gigantspinosaurus (Xing, Peng & Shu, 2008;Christiansen & Tschopp, 2010)] ornithischians. This broad distribution implies that the presence of feature scales is plesiomorphic for Dinosauria. ...
... This broad distribution implies that the presence of feature scales is plesiomorphic for Dinosauria. The dome-like feature scales of Carnotaurus and Albertosaurus are also present in the Auca Mahuevo titanosaur embryos (Coria & Chiappe, 2007, figure 1.6) as well as some hadrosaurs (Bell, 2012) and stegosaurs (Christiansen & Tschopp, 2010, figure 5). These domed feature scales differ from the flat feature scales covering the skin of the ceratopsids Centrosaurus (Brown, 1917, plate 13) and Chasmosaurus (Sternberg, 1925), and some hadrosaurs (Bell, 2012, as well as the feature scales with a nipple-like structure present in Triceratops (HMNS PV.1506). ...
Modern birds are typified by the presence of feathers, complex evolutionary innovations that were already widespread in the group of theropod dinosaurs (Maniraptoriformes) that include crown Aves. Squamous or scaly reptilian-like skin is, however, considered the plesiomorphic condition for theropods and dinosaurs more broadly. Here, we review the morphology and distribution of non-feathered integumentary structures in non-avialan theropods, covering squamous skin and naked skin as well as dermal ossifications. The integumentary record of non-averostran theropods is limited to tracks, which ubiquitously show a covering of tiny reticulate scales on the plantar surface of the pes. This is consistent also with younger averostran body fossils, which confirm an arthral arrangement of the digital pads. Among averostrans, squamous skin is confirmed in Ceratosauria (Carnotaurus), Allosauroidea (Allosaurus, Concavenator, Lourinhanosaurus), Compsognathidae (Juravenator), and Tyrannosauroidea (Santanaraptor, Albertosaurus, Daspletosaurus, Gorgosaurus, Tarbosaurus, Tyrannosaurus), whereas dermal ossifications consisting of sagittate and mosaic osteoderms are restricted to Ceratosaurus. Naked, non-scale bearing skin is found in the contentious tetanuran Sciurumimus, possibly ornithomimosaurians (Pelecanimimus) and tyrannosauroids (Santanaraptor), and also on the patagia of scansoriopterygids (Ambopteryx, Yi). Scales are surprisingly conservative among non-avialan theropods compared to some dinosaurian groups (e.g. hadrosaurids); however, the limited preservation of tegument on most specimens hinders further interrogation. Scale patterns vary among and/or within body regions in Carnotaurus, Concavenator and Juravenator, and include polarised, snake-like ventral scales on the tail of the latter two genera. Unusual but more uniformly distributed patterning also occurs in Tyrannosaurus, whereas feature scales are present only in Albertosaurus and Carnotaurus. Few theropods currently show compelling evidence for the co-occurrence of scales and feathers (e.g. Juravenator, Sinornithosaurus), although reticulate scales were probably retained on the mani and pedes of many theropods with a heavy plumage. Feathers and filamentous structures appear to have replaced widespread scaly integuments in maniraptorans. Theropod skin, and that of dinosaurs more broadly, remains a virtually untapped area of study and the appropriation of commonly used techniques in other palaeontological fields to the study of skin holds great promise for future insights into the biology, taphonomy and relationships of these extinct animals.
... Many species of extinct vertebrates are known from single specimens (Watanabe 2016;Tschopp and Upchurch 2019), rendering any morphological comparison necessarily typological. Additionally, possible comparisons are mainly restricted to hard tissues, given that the morphology of soft tissues only preserves in exceptional circumstances (e.g., Christiansen and Tschopp 2010;Rauhut et al. 2012;Zheng et al. 2017;Fabbri et al. 2020;Bell and Hendrickx 2021). Even the preserved fossil hard parts are often incomplete, hampering comparison among extinct taxa and between extinct and extant taxa (e.g., Mannion and Upchurch 2010;Cleary et al. 2015;Brown et al. 2019). ...
Generally, the species is considered to be the only naturally occurring taxon. However, species recognised and defined using different species delimitation criteria cannot readily be compared, impacting studies of biodiversity through Deep Time. This comparability issue is particularly marked when comparing extant with extinct species, because the only available data for species delimitation in fossils is derived from their preserved morphology, which is generally restricted to osteology in vertebrates. Here, we quantify intraspecific, intrageneric, and intergeneric osteological variability in extant species of lacertid lizards using pairwise dissimilarity scores based on a dataset of 253 discrete osteological characters for 99 specimens referred to 24 species. Variability is always significantly lower intraspecifically than between individuals belonging to distinct species of a single genus, which is in turn significantly lower than intergeneric variability. Average values of intraspecific variability and associated standard deviations are consistent (with few exceptions), with an overall average within a species of 0.208 changes per character scored. Application of the same methods to six extinct lacertid species (represented by 40 fossil specimens) revealed that intraspecific osteological variability is inconsistent, which can at least in part be attributed to different researchers having unequal expectations of the skeletal dissimilarity within species units. Such a divergent interpretation of intraspecific and interspecific variability among extant and extinct species reinforces the incomparability of the species unit. Lacertidae is an example where extant species recognised and defined based on a number of delimitation criteria show comparable and consistent intraspecific osteological variability. Here, as well as in equivalent cases, application of those skeletal dissimilarity values to palaeontological species delimitation potentially provides a way to ameliorate inconsistencies created by the use of morphology to define species.
... C. Hendrickx and P.R. Bell Cretaceous Research 128 (2021) 104994 present in other large theropods such as tyrannosaurids as well as some stegosaurids and hadrosaurids (Christiansen and Tschopp, 2010;Bell 2014;Bell et al. 2017;Hendrickx et al., in press). These small basement scales differ from significantly larger basement scales seen in mature individuals of sauropods, ankylosaurs, and ceratopsians (Brown 1917;Sternberg 1925;Czerkas 1994;Gim enez 2007;Arbour et al. 2014;Brown 2017;Hendrickx et al., in press;Fig. ...
The integument of the theropod dinosaur Carnotaurus sastrei from the Upper Cretaceous of Argentina is here described in detail for the first time. The scaly skin of this abelisaurid is the most completely preserved of any theropod and the only example of this form of integument known outside of Tetanurae (excluding footprints). The skin is preserved in the shoulder, thoracic, tail and, possibly, neck regions and consists of medium to large (20-65 mm in diameter) conical feature scales surrounded by a network of low and small (<14 mm) basement scales separated by narrow interstitial tissue. Contrary to previous interpretations, the feature scales are randomly distributed and neither form discrete rows nor show progressive variations in their size along parts of the body. They also show little difference in morphology along the body, although their apices are variously positioned in different body parts. Conversely, the basement scales vary from small and elongated, large and polygonal, and circular-to-lenticular in the thoracic, scapular, and tail regions, respectively. Given the presumed active lifestyle of Carnotaurus and the necessity of shedding excess heat, particularly at large body sizes (>1000 kg), we speculate that the skin may have played a vital role in thermoregulation; a role consistent with integument function in extant mammals and reptiles.
... The integument consists of non-overlapping scales, or tubercles, similar to those observed on other dinosaur skin fossils (e.g., Arbour et al., 2014;Bell, 2014;Christiansen & Tschopp, 2010;Czerkas, 1994;Czerkas & Czerkas, 1997;Kim et al., 2010). There is integument on both sides of the rib MDS-2019-010 (Fig. 1). ...
The life appearance of dinosaurs is a hotly debated topic in the world of paleontology, especially when it comes to dinosaur integument. In the case of sauropods, however, the topic is harder to properly discuss due to the limited amount of fossilized skin impressions that have been discovered. Thus far, the fossil record of sauropod integument fossils include titanosaur embryos from Patagonia, possible keratinous diplodocid dorsal spines, track ways with foot impressions, and other isolated skin impressions found in association with sauropod body fossils. Several prominent integument fossils have been found at the Mother’s Day Quarry, located in the Bighorn Basin, Montana. These discoveries may bring new important information about diplodocids, specifically Diplodocus sp. Here we describe newly uncovered fossilized skin that gives evidence of scale diversity in the genus Diplodocus . The scales themselves represent tubercles, and exhibit various shapes including rectangular, ovoid, polygonal, and globular scales. The tubercles are small in size, the biggest of which only reach about 10mm in length. Considering how diverse the scale shapes are in such a small area of skin, it is possible that these distinct scale shapes may represent a transition on the body from one region to another: perhaps from the abdomen to dorsal side, or abdomen to shoulder. Based on analysis of extant integument and scale orientation of crocodilians, it is possible to hypothesize on the location of the integument relative to the body as well as the size and relative maturational status of the individual.
... The parasagittal plates of stegosaurs are generally considered to show little evidence of a biomechanical function in defence because their thin, highly vascularized cortex and cancellous interior could have been easily penetrated and crushed by the teeth of any large predator (Main et al., 2005). However, as in ankylosaurs, a keratinous sheath that certainly covered these osteoderms could have provided sharp edges and extra mechanical protection (Christiansen and Tschopp, 2010). Furthermore, the iconic large, flat and blunt dorsal plates characteristic of Stegosaurus stenops, that are almost stereotypically associated with stegosaurs, are more the exception rather than the rule concerning general stegosaurian osteoderm morphology. ...
Gregarious behaviour of large bodied herbivorous dinosaurs, such as ceratopsians, hadrosaurs and
sauropods, has received much attention due to their iconic mass death assemblages (MDAs). Yet, social
lifestyle of ankylosaurs, a highly specialized group of armoured herbivores that flourished predominantly
during the Cretaceous Period, remains largely ambiguous. Whereas most ankylosaurs are found as isolated
individuals, which may suggest a dominantly solitary lifestyle, the few examples of ankylosaur
MDAs indicate that some members of this clade could have been gregarious. In this review, we assess
taphonomic history, ontogenetic composition of the MDAs, defence system and other comparative
anatomical attributes, and inferred habitat characteristics of ankylosaurs; aspects that may indicate and/
or influence group formation in extant herbivores and can also be studied in fossils. We show that the
ankylosaurian gross anatomy, such as their heavy armour, barrel-shaped body and usually stocky limbs,
combined with the rarity of their MDAs and multiple parallel trackways, all suggest a solitary adult life
with efficient anti-predator defence system, limited agility, and confined foraging range. However,
characteristics of the known MDAs of Pinacosaurus, Gastonia, and the Iharkút nodosaurids evaluated in
this study imply that at least some ankylosaurs formed groups. Nevertheless, we found no common and
consistent set of features to explain why these particular ankylosaurs were gregarious. While inefficient
anti-predator defence along with likely higher agility of juvenile Pinacosaurus living in open habitats
could account for their gregarious behaviour, such ontogenetic, anatomical and habitat features are not
combined either in Gastonia or in the Iharkút nodosaurid MDAs. Instead, members of each MDA likely
had their own specific conditions driving them to form relatively small herds, indicating a more complex
social structuring in ankylosaurs than previously acknowledged. Studying morphological and functional
disparity within Ankylosauria may help explain the repertoire of their social behaviour. Our holistic
approach shows that combining palaeontological and biological information is essential and can provide
new insights into the behavioural ecology of long extinct vertebrates.
... The primitive condition in diapsids is for the body scales to be arranged into an irregular or semiregular mosaic over most of the body, but often with larger scales or scutes regularly arranged along the back (Chang et al. 2009). Such a pattern is seen in many non-avian dinosaurs including hadrosaurids (Bell 2014), ceratopsians (Vinther et al. 2016), thyreophorans (Christiansen and Tschopp 2010;Arbour et al. 2014), and sauropods (Chiappe et al. 1998) and more distant relatives of birds including crocodylians (Grigg and Kirshner 2015), turtles, and many lepidosaurs (Pianka and Vitt 2003), as well as on the feet of birds (Lucas and Stettenheim 1972). ...
The Jurassic stem bird Archaeopteryx is an iconic transitional fossil, with an intermediate morphology combining features of non-avian dinosaurs and crown Aves. Importantly, fossils of Archaeopteryx preserve not only the bones but also details of the plumage and therefore help shed light on the evolution of feathers, wings, and avian flight. Plumage is preserved in multiple individuals, allowing a detailed documentation of the feathers of the wings, tail, hindlimbs, and body. In some features, Archaeopteryx’ plumage is remarkably modern, yet in others, it is strikingly primitive. As in extant birds, remiges and coverts are enlarged and overlap to form airfoils. Remiges and rectrices exhibit asymmetrical, pennaceous vanes, with interlocking barbules. The hindlimbs bear large, vaned feathers as in Microraptor and Anchiornis. Rectrices are numerous and extend the full length of the tail to the hips. The plumage of crown Aves was assembled in a stepwise fashion from Anchiornis through Archaeopteryx, culminating in a modern arrangement in ornithothoracines. Subsequent stasis in feather and wing morphology likely reflects aerodynamic and developmental constraints. Feather morphology and arrangement in Archaeopteryx are consistent with lift-generating function, and the wing loading and aspect ratio are comparable to modern birds, consistent with gliding and perhaps flapping flight. The plumage of Archaeopteryx is intermediate between Anchiornis and more derived Pygostylia, suggesting a degree of flight ability intermediate between the two.
... The most conspicuous structures are a large patch of tubercle-like structures along the laterodorsal side of the tail between the 9th and 18th caudal and a series of longitudinal orientated fibre-like structures along the ventral side of the tail between the 12th and 15th caudal (Fig. 6.2a), which are even visible under normal light conditions (see Chiappe and Göhlich 2010). The former structure was originally described as uniformly sized, nonoverlapping, smooth tuberclelike scales, as known from various dinosaur taxa (Osborn 1912;Czerkas 1997;Mayr et al. 2002;Coria and Chiappe 2007;Christiansen and Tschopp 2010;Bell 2012Bell , 2014, while the latter was interpreted as possible remains of tendinal elements of the m. ilioischiocaudalis, remains of a reinforced layer of the vertical septum ventral to the chevrons or bundles of subcutaneous collagen fibres (see Göhlich and Chiappe 2006;Göhlich et al. 2006;Chiappe and Göhlich 2010). ...
... The primitive condition in diapsids is for the body scales to be arranged into an irregular or semiregular mosaic over most of the body, but often with larger scales or scutes regularly arranged along the back (Chang et al. 2009). Such a pattern is seen in many non-avian dinosaurs including hadrosaurids (Bell 2014), ceratopsians , thyreophorans (Christiansen and Tschopp 2010;Arbour et al. 2014), and sauropods (Chiappe et al. 1998) and more distant relatives of birds including crocodylians (Grigg and Kirshner 2015), turtles, and many lepidosaurs (Pianka and Vitt 2003), as well as on the feet of birds (Lucas and Stettenheim 1972). ...
... Most of our information comes from hadrosaurids, ceratopsians, and ankylosaurs, with rare examples from non-hadrosaurid ornithopods, heterodontosaurids, and stegosaurs. The majority of taxa possess flattened, non-overlapping, polygonal scales over most of the body surface, exemplified by numerous hadrosaurid specimens with extensive skin preservation, including almost complete skin envelopes (see reviews in Bell 2012Bell , 2014Davis 2014), but as also seen in a range of thyreophoran and ceratopsian taxa (e.g. Brown 1917;Christiansen and Tschopp 2010;Arbour et al. 2014). Skin preservation is of high enough quality and extent in some hadrosaurid taxa that differences in squamation patterns can be used for taxonomic purposes (Bell 2012). ...
Several stem birds, such as Confuciusornithidae and Enantiornithes, were characterized by the possession of one or two pairs of conspicuous, elongated tail feathers with a unique morphology, so-called rhachis-dominated racket plumes. In the past, several studies reported contradictory interpretations regarding the morphology of these feathers, which sometimes failed to match with any morphology known from modern feathers. In this chapter, these interpretations are reviewed and compared with various modern feather types. The comparison confirms recent interpretations that the rhachis-dominated racket plumes are highly modified pennaceous feathers with ornamental function, originating at least two times independently from each other during evolution. While the gross organization (i.e., a short distal vane and a long, naked rhachis) of these feathers resembles that of filoplumes, they resemble pennaceous body feathers of penguins in terms of rhachis morphology and pigmentation pattern. As the rhachis-dominated racket plumes combine different morphologies that are apparent among modern feather types, this extinct morphotype does in fact not show any aberrant morphological novelties, but rather fall into the morphological and developmental spectrum of modern feathers.
... The most conspicuous structures are a large patch of tubercle-like structures along the laterodorsal side of the tail between the 9th and 18th caudal and a series of longitudinal orientated fibre-like structures along the ventral side of the tail between the 12th and 15th caudal (Fig. 6.2a), which are even visible under normal light conditions (see Chiappe and Göhlich 2010). The former structure was originally described as uniformly sized, nonoverlapping, smooth tuberclelike scales, as known from various dinosaur taxa (Osborn 1912;Czerkas 1997;Mayr et al. 2002;Coria and Chiappe 2007;Christiansen and Tschopp 2010;Bell 2012Bell , 2014, while the latter was interpreted as possible remains of tendinal elements of the m. ilioischiocaudalis, remains of a reinforced layer of the vertical septum ventral to the chevrons or bundles of subcutaneous collagen fibres (see Göhlich and Chiappe 2006;Göhlich et al. 2006;Chiappe and Göhlich 2010). ...
... The primitive condition in diapsids is for the body scales to be arranged into an irregular or semiregular mosaic over most of the body, but often with larger scales or scutes regularly arranged along the back (Chang et al. 2009). Such a pattern is seen in many non-avian dinosaurs including hadrosaurids (Bell 2014), ceratopsians , thyreophorans (Christiansen and Tschopp 2010;Arbour et al. 2014), and sauropods (Chiappe et al. 1998) and more distant relatives of birds including crocodylians (Grigg and Kirshner 2015), turtles, and many lepidosaurs (Pianka and Vitt 2003), as well as on the feet of birds (Lucas and Stettenheim 1972). ...
... Most of our information comes from hadrosaurids, ceratopsians, and ankylosaurs, with rare examples from non-hadrosaurid ornithopods, heterodontosaurids, and stegosaurs. The majority of taxa possess flattened, non-overlapping, polygonal scales over most of the body surface, exemplified by numerous hadrosaurid specimens with extensive skin preservation, including almost complete skin envelopes (see reviews in Bell 2012Bell , 2014Davis 2014), but as also seen in a range of thyreophoran and ceratopsian taxa (e.g. Brown 1917;Christiansen and Tschopp 2010;Arbour et al. 2014). Skin preservation is of high enough quality and extent in some hadrosaurid taxa that differences in squamation patterns can be used for taxonomic purposes (Bell 2012). ...
Feathers are a characteristic of modern birds that differentiate them from all other extant non-avian reptiles. The origin of feathers goes back deep into the Mesozoic, preceding the origin of flight, and early protofeathers were probably present in the ancestral Tetanurae, Dinosauria, or even Ornithodira. Among extant vertebrates, the feathers of modern birds are morphologically the most complex integumentary structure with enormous shape diversity resulting from a hierarchical organization of repetitive morphological and developmental modules. In this chapter, the morphological ground patterns of modern feathers, their underlying developmental processes, and the biological roles of different feather types are reviewed.
... Most of our information comes from hadrosaurids, ceratopsians, and ankylosaurs, with rare examples from non-hadrosaurid ornithopods, heterodontosaurids, and stegosaurs. The majority of taxa possess flattened, non-overlapping, polygonal scales over most of the body surface, exemplified by numerous hadrosaurid specimens with extensive skin preservation, including almost complete skin envelopes (see reviews in Bell 2012Bell , 2014Davis 2014), but as also seen in a range of thyreophoran and ceratopsian taxa (e.g. Brown 1917;Christiansen and Tschopp 2010;Arbour et al. 2014). Skin preservation is of high enough quality and extent in some hadrosaurid taxa that differences in squamation patterns can be used for taxonomic purposes (Bell 2012). ...
Over the last two decades, the dinosaur fossil record has revealed much about the nature of their epidermal structures. These data challenged long-standing hypotheses of widespread reptile-like scalation in dinosaurs and provided additional evidence that supported the deeply nested position of birds within the clade. Moreover, in recent years, the discovery of filamentous structures in numerous species across the dinosaurian evolutionary tree suggests a model of deep feather homology within dinosaurs, with the appearance of feathers hypothesised to coincide with the dinosaur origin. Thanks to phylogenetic comparative methods, these homologies can now be tested empirically and form the basis of this study. Based on a dataset of 77 dinosaur species that preserve integumentary structures, we undertake a series of model-fitting and ancestral state reconstruction analyses to interpret the evolutionary history and ancestral integumentary condition in dinosaurs. Our results provide the first empirical support for the evolution of feathers in an ordered fashion, but reveal that these evolutionary trends were not always towards ‘more complex’ conditions. Ancestral state reconstructions demonstrate that irrespective of the preferred phylogenetic framework, the ancestral pterosaur condition or whether any one major dinosaur lineage had a Late Triassic-feathered representative, support values for a filamentous/feathered dinosaur ancestor are low. More examples of feathered taxa from across the dinosaur tree, and in particular the discovery of as yet unknown feathered Triassic taxa, will be needed in order to overturn current support for a scaly dinosaurian ancestor.
... The most conspicuous structures are a large patch of tubercle-like structures along the laterodorsal side of the tail between the 9th and 18th caudal and a series of longitudinal orientated fibre-like structures along the ventral side of the tail between the 12th and 15th caudal ( Fig. 6.2a), which are even visible under normal light conditions (see Chiappe and Göhlich 2010). The former structure was originally described as uniformly sized, nonoverlapping, smooth tuberclelike scales, as known from various dinosaur taxa (Osborn 1912;Czerkas 1997;Mayr et al. 2002;Coria and Chiappe 2007;Christiansen and Tschopp 2010;Bell 2012Bell , 2014, while the latter was interpreted as possible remains of tendinal elements of the m. ilioischiocaudalis, remains of a reinforced layer of the vertical septum ventral to the chevrons or bundles of subcutaneous collagen fibres (see Chiappe and Göhlich 2010). ...
The discoveries of numerous theropod dinosaurs with filamentous integumentary structures in various stages of morphological complexity from the Upper Jurassic and Lower Cretaceous of China provided striking evidence that birds represent modern predatory dinosaurs and that feathers were originally filamentous. In the shadow of these impressive discoveries, two early juvenile theropod dinosaurs from the Upper Jurassic limestones of Bavaria (Germany), Juravenator starki and Sciurumimus albersdoerferi, were described. Both are preserved with phosphatized soft tissues, including skin and feathers. In the current study, the integumentary structures of both theropods are investigated and revised with the help of autofluorescence methods, using two different excitation wavelengths (UVA and cyan). Both theropods possessed monofilamentous feathers and scaleless skin. In J. starki, short feathers could only be traced in the tail region. The tubercle-like structures, originally described as scales, found in the anterior tail region of J. starki, show no autofluorescence signal and were reinterpreted as remains of adipocere, maybe indicating the presence of a fat body. S. albersdoerferi was probably entirely plumaged, possessing a filamentous crest on the dorsal edge in the anterior tail section. This current example emphasizes the importance of taphonomic reviews for the interpretation of integumentary structures. Furthermore, the new data give new insights into the early evolution of feathers. However, the placement of J. starki in multiple phylogenetic positions and differences in the morphological interpretation of filamentous feathers found in basal coelurosaurs produce contrasting reconstructions of character evolution that will need to be resolved in due course if greater clarity is to be obtained in this area.
