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Skin pathology in the Cretaceous: Evidence for probable failed predation in a dinosaur

Authors:
Bruce Rothschild at University of Kansas
Bruce Rothschild
Robert A Depalma at The University of Manchester
Robert A Depalma
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Examination of preserved skin from a duckbill dinosaur revealed disruption of the normal scale pattern and replacement by granulation tissue. Wrinkles radiating outward from the scar document wound contraction similar to that seen in modern injuries. This is the first unequivocal report of dinosaur tissue response to dermal pathology and evidences behavior – escape from a predator.
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Please cite this article in press as: Rothschild, B.M., Depalma, R., Skin pathology in the Cretaceous: Evidence for probable failed predation in
a dinosaur, Cretaceous Research (2013), http://dx.doi.org/10.1016/j.cretres.2013.01.005
Cretaceous Research xxx (2013) 1e4
Skin pathology in the Cretaceous: Evidence for probable failed predation
in a dinosaur
Bruce M. Rothschild
a, b,
*
, Robert Depalma
c
a
Biodiversity Institute, University of Kansas, Lawrence, KS 66045, USA
b
Department of Medicine, Northeast Ohio Medical University, Rootstown, OH 44505, USA
c
Department of Paleontology, Palm Beach Museum of Natural History, Ft. La uderdale, FL 33306, USA
a r t i c l e i n f o
Article history:
Received 1 October 2012
Accepted in revised form 12 January 2013
Available online xxx
Keywords:
Wound healing
Dinosaur
Hadrosaur
Pathology
Paleopathology
a b s t r a c t
Examina tion of preserved skin from a duckbill dinosaur revealed disruption of the normal scale pattern
and replacement by granulation tissue. Wrinkles radiating outward from the scar document wound
contraction similar to that seen in modern injuries. This is the
fi
rst unequivocal report of dinosaur tissue
response to dermal pathology and evidences behavior e escape from a predator.
©
2013 Elsevier Ltd. All rights reserved.
1.
Introduction
Lingham-Soliar (2008) recognized traumatic skin damage in an
ancestor of ceratopsia (horned dinosaurs),
Psittacosaurus
. He
reported two concave skin indentations with radiating stress frac-
tures, which he related to a tearing impression produced by teeth
from an unknown predator or scavenger. This was apparently the
fi
rst recognition of skin pathology in a dinosaur and perhaps in the
paleontologic record (Rothschild and Martin, 2006; Tanke and
Rothschild, 2002). He could not distinguish predation and scav-
enging, as there was no evidence of healing. The injured dinosaur
could have been dead at the time of skin injury or may have sur-
vived, but died too soon after injury for healing to be
recognizeddeven histologically. We report the
fi
rst macroscopic
evidence of skin wound healing in a dinosaur, evidence of a prior
traumatic event, possibly of a predation effort.
2.
Methods
The hadrosaur skin (Palm Beach Museum of Natural History
PBMNH.P.06.016.T) examined in this paper was found in
*
Corresponding author. Biodiversity Institute, University of Kansas, Lawrence, KS
66045, USA.
E-mail addresses:
bmr@ku.edu (B.M. Rothschild), paleogen@aol.com
(R. Depalma).
association with a large adult duckbill dinosaur (
Edmontosaurus
annectens
) skull, in Harding County, South Dakota (DePalma, 2010).
The specimens were excavated from medium- to coarse-grained
crevasse-splay deposits in the Upper Hell Creek Formation (Late
Maastrichtian, 67.6e65.5 million years before present) (Hicks et al.,
2002). The skin was discovered in juxtaposition to the skull, which
bears examples of healed bone following trauma from a predator
attack (Fig. 1A and B). The spacing of large tooth drags on the skull
bones is consistent with a very large tyrannosaurid, probably
Tyrannosaurus rex
.
3.
Results
The patch of preserved skin measures approximately 12.25 cm
by 14 cm, and consists of numerous small, polygonal, non-
overlapping tubercles (Fig. 1C). The tubercles range in size from 2
to 6 mm, and are of similar morphology to those described for other
Edmontosaurus
specimens (Fig. 2). The normal scale pattern was
focally disrupted, where the skin had been punctured/lacerated and
replaced by granulation tissue. The oblong scar measures 1.3 cm by
3.5 cm. A series of wrinkles radiating outward from the scar are
similar to those that can emerge following
fi
nal contraction of
wounds in modern dermal injuries (Fig. 3). Tubercles are remark-
ably smaller and arranged in a chaotic pattern around the periphery
of the scar, a common characteristic observed in healed modern
reptilian skin (Fig. 3A).
0195-6671/$ e see front matter
©
2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.cretres.2013.01.005
Contents lists available at SciVerse ScienceDirect
Cretaceous Research
jo urnal hom epa ge: www . el s ev i er. c om / loc ate / Cr e tRe s
2
B.M. Rothschild, R. Depalma / Cretaceous Research xxx (2013) 1
e
4
Please cite this article in press as: Rothschild, B.M., Depalma, R., Skin pathology in the Cretaceous: Evidence for probable failed predation in
a dinosaur, Cretaceous Research (2013), http://dx.doi.org/10.1016/j.cretres.2013.01.005
Fig. 1.
A, dorsal v iew of an
Edmontosaurus
braincase, showing extensive healed trauma from a predator attack. Red highlights indicate affected areas, and bold black line indicates
the normal skull o utline f or the right s ide. B, the same braincase in dorsolateral oblique view, with arrows pointing to individual healed tooth drag marks. At the tip of the center
arrow is a w3 cm diameter abscess. C, a patch of fossil skin from the sam e animal, showing a w3.5 cm oblong area of healed dermal trauma. (For interpretation of the references to
colour in this
fi
gure legend, the reader is referred to the web version of this article.)
4.
Discussion
Studies on mammals have been the major source of information
on wound healing. Once the external body layer (skin) is compro-
mised, wound healing is initiated in a series of sequential, but
overlapping phases. Platelets migrate to the wound to establish
hemostasis. Bacteria and debris are phagocytized in the in
fl
am-
matory phase, which sets the stage for granulation tissue forma-
tion. This phase, which reaches peak in 1e2 weeks in mammals and
which is slowed by wound edge movement, allows recovering of
the wound (epithelialization, which takes between 17 and 30 days
in humans) and subsequent wound contraction (which lasts several
weeks), restoring skin strength (Nguyen et al., 2009; Stadelmann
et al., 1998). The last maturation phase may last as long as a year
(Mercandetti and Cohen, 2008).
Reptilian skin wounds heal in a manner similar to that observed
in mammals, but more slowly, with wound cohesiveness restored
only at 4e6 weeks (Ballard and Cheek, 2003; Bennett, 1089a,b;
Frye, 1981; Mitchell and Diaz-Figueroa, 2004; Smith and Barker,
1988; Smith et al., 1988). Cohesiveness implies that the freely
movable edges of the wound are now immobile, as occurs in the
in
fl
ammatory phase of wound healing. Lizards have minimal scab
Please cite this article in press as: Rothschild, B.M., Depalma, R., Skin pathology in the Cretaceous: Evidence for probable failed predation in
a dinosaur, Cretaceous Research (2013), http://dx.doi.org/10.1016/j.cretres.2013.01.005
B.M. Rothschild, R. Depalma / Cretaceous Research xxx (2013) 1
e
4
3
Fig. 2.
Fossil
Edmontosaurus
skin A, compared with the present specimen B, Image in A
courtesy Black Hills Institute of Geological Research.
specimen base, even if extrapolation of
fi
ndings to other hadrosaurs
is valid. In this instance, dermal impressions were recognized and
logged during the excavation process, providing direct evidence for
its location.
Preservation of dinosaur skin may be more common than we
had been led to believe. It certainly is common in the Lower Cre-
taceous Yixian Formation in Liaoning Province, China (Lingham-
Soliar, 2008). Aggressive excavation of underlying bone may be
responsible for that oversight in North America. Healing skin in-
juries appear to be rare in the fossil record for good reason e prey
rarely escapes once the attacker latches onto it. In this instance, the
nature (healing of the residua of the anterior portion of the
“muzzle” of the skull (Fig. 1) clearly documents predation. While
this is the
fi
rst unequivocal report of dinosaur tissue response to
dermal pathology, systematic evaluation of skin by individuals
trained to recognize subtle alterations is likely to be a fruitful and
stimulating area for future investigation. Just as histopathologic
examination of dinosaur bones and eggs has led to many insights
(Tanke and Rothschild, 2002), similar examination of skin is rec-
ommended for future study.
Fig. 3.
A healed dermal injury in a modern iguana A, compared with the healed dinosaur skin B. Notice the overall similarity in morphology of the heal ed skin, particularly the
amorphous central area of granulation tissue (1), w hich is circumscrib ed by a ring of disrupted scale pattern, with outwardly radiating wrinkles (2).
formation and minimal in
fl
ammatory response. This does contrast
with neutrophil and subsequent macrophage response in mam-
mals. Study in garter snake
Thamnophis sirtalis
revealed that the
disrupted scale pattern persisted 3e6 weeks, dependent on ambi-
ent temperature (Smith et al., 1988).
Most of the direct evidence on prey species is ambiguous
because the damage in
fl
icted upon an animal during a successful
hunt mirrors injury resulting from scavenging behavior, making
a distinction between the two modes of food procurement virtually
impossible (Brain, 1981; Horner and Lessem, 1993; Currie and
Jacobsen, 1995; Jacobsen, 1995, 2001; Farlow and Holtz, 2002;
Fastovsky and Smith, 2004). Healed injuries provide the most un-
equivocal evidence of predation (Farlow and Holtz, 2002; Rogers,
1990; Williamson, 1996).
Attributing a location to a given skin impression contributes
additional information. Bell’s (2012) description of location-related
variation of skin impressions in
Saurolophus
could not be applied in
this instance, as cranial skin was inadequately represented in his
Acknowledgments
Gratitude and appreciation are owed to the following people
and institutions for their roles in the execution of this study:
D. Burnham, L.D. Martin, T. Smith, R. Smith, R. Smith, R. DePalma Sr.,
M. Cox, P. Larson and the Black Hills Institute of Geological
Research, M. Triebold, W. Stein and family, F. Cichocki, R. Feeney, FB.
Pedrazzoli, T. Pedrazzoli, the University of Kansas Department of
Geology, the University of Kansas Department of Biology, K. Holrah,
A. Oleinik, E. Petuch, T. Jacobs, B. Lindsey and Family, S. Marty and
family, P. Bjork, K. Carpenter, R. Bakker, and J. Gurche.
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4
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... These analyses also allow, by means of exploration of types of skeletal damages, their frequencies and putative underlying causes and to infer paleoecological and behavioural aspects of extinct populations (Moodie, 1918;Rothschild and Martin, 2006;Pardo Perez et al., 2018b). Paleopathologies in fossil vertebrates are usually identified only if they damage or alter the skeleton but see Rothschild and Depalma (2013). When damage is the result of a traumatic injury (e.g., fractures) the bones develop callus during healing. ...
... Both diseases have previously been recognized in mosasaur vertebrae (Rothschild and Martin, 2006;Rothschild et al., 2012a;Rothschild and Everhart, 2015). The former is characterized by erosions with reactive new bone formation (Rothschild and Woods, 1991;Resnick, 2002); the latter, by disorganized trabecular patterns underlying the articular surface (Resnick, 2002;Rothschild and Martin, 2006;Rothschild et al., 2012a). The spheroid defect recognized radiologically and presences of the surface defect (indicative of a draining sinus) are parsimonious with the diagnosis of infectious arthritis. ...
... Both diseases have previously been recognized in mosasaur vertebrae (Rothschild and Martin, 2006;Rothschild et al., 2012a;Rothschild and Everhart, 2015). The former is characterized by erosions with reactive new bone formation (Rothschild and Woods, 1991;Resnick, 2002); the latter, by disorganized trabecular patterns underlying the articular surface (Resnick, 2002;Rothschild and Martin, 2006;Rothschild et al., 2012a). The spheroid defect recognized radiologically and presences of the surface defect (indicative of a draining sinus) are parsimonious with the diagnosis of infectious arthritis. ...
A pathological scapula in a mosasaur from the upper Maastrichtian of Antarctica: Evidence of infectious arthritis and spondyloarthropathy
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We describe infectious arthritis and spondyloarthropathy in a juvenile mosasaur recovered from the upper Maastrichtian of Antarctica, representing the first report of a skeletal pathology of a mosasaur from the southern hemisphere. Macroscopic examination of the scapula revealed a remodelled, deeply excavated and expanded gleno-humeral joint with adjacent linear disruption. X-ray examination revealed a deep excavation expanding the glenoid fossa, with disorganized subchondral bone and a focal spherical defect. The individual did not continue to grow for a long time after the appearance of the lesion. Although not directly related to the mosasaur death, this condition may have contributed to the demise of the animal by reducing its effectiveness at obtaining food or increasing susceptibility to fatal disease, additional injury, or even predation.
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... Subadult tyrannosaurids mandibles experienced relatively low von Mises stresses in contrast to the mature individuals; this suggests that subadult or smaller tyrannosaurid genera fed on smaller, potentially more agile prey, while the bone-crunching bite used by mature individuals was reserved for large, less mobile prey, such as hadrosaurids. Hadrosaurids were large, herbivorous duck-billed dinosaurs such as Edmontosaurus (Figure 14) which possess ample evidence for active predation from tyrannosaurs (Carpenter, 1997;Hone & Watabe, 2010;Rothschild & DePalma, 2013). ...
... In Maastrichtian (72.1-66 million years old) North America, T. rex was considered the apex tyrannosaurid; skin pathologies (Rothschild & DePalma, 2013), healed prey vertebrae containing teeth (De Palma, Burnham, Martin, Rothschild, & Larson, 2013), and coprolite or fossil feces analyses (Chin, Tokaryk, Erickson, & Calk, 1998) indicate an active predatory lifestyle. The extent of active predation in Tyrannosaurus has remained a contentious topic for decades (Holtz Jr., 2008;Horner, 1994Horner, , 1997. ...
Biomechanics of juvenile tyrannosaurid mandibles and their implications for bite force: Evolutionary biology
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The tyrannosaurids are among the most well‐studied dinosaurs described by science, and analysis of their feeding biomechanics allows for comparison between established tyrannosaurid genera and across ontogeny. 3D finite element analysis (FEA) was used to model and quantify the mechanical properties of the mandibles (lower jaws) of three tyrannosaurine tyrannosaurids of different sizes. To increase evolutionary scope and context for 3D tyrannosaurine results, a broader sample of validated 2D mandible FEA enabled comparisons between ontogenetic stages of Tyrannosaurus rex and other large theropods. It was found that mandibles of small juvenile and large subadult tyrannosaurs experienced lower stress overall because muscle forces were relatively lower, but experienced greater simulated stresses at decreasing sizes when specimen muscle force is normalized. The strain on post‐dentary ligaments decreases stress and strain in the posterior region of the dentary and where teeth impacted food. Tension from the lateral insertion of the looping m. ventral pterygoid muscle increases compressive stress on the angular but may decrease anterior bending stress on the mandible. Low mid‐mandible bending stresses are congruent with ultra‐robust teeth and high anterior bite force in adult T. rex. Mandible strength increases with size through ontogeny in T. rex and phylogenetically among other tyrannosaurids, in addition to that tyrannosaurid mandibles exceed the mandible strength of other theropods at equivalent ramus length. These results may indicate separate predatory strategies used by juvenile and mature tyrannosaurids; juvenile tyrannosaurids lacked the bone‐crunching bite of adult specimens and hunted smaller prey, while adult tyrannosaurids fed on larger prey.
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... Deep, raking furrows and punctures are present on the tail (Fig 8) and additional penetrative marks are present on the skin of the right manus and forelimb, the latter of which was partially degloved in the feeding process. While bite and claw marks on bone often preserve anatomical characteristics of the trace making structure, skin and other soft tissues deform more readily, especially in the event of subsequent healing or decomposition, a feature that confounds efforts to use injuries to identify specific sources of the subsequent damage in forensic [46] and paleontological [56] contexts, though major clades possibly can still be differentiated [46]. Fortunately, there are additional bite marks on the bones of this specimen, and those present on the right humerus and radius (Figs 5E, 5F and 6B-6E) are diagnostic of a crocodyliform trace maker [25][26][27]. ...
Biostratinomic alterations of an Edmontosaurus "mummy" reveal a pathway for soft tissue preservation without invoking "exceptional conditions"
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Removal or protection from biostratinomic agents of decomposition, such as predators and scavengers, is widely seen as a requirement for high-quality preservation of soft tissues in the fossil record. In this context, extremely rapid burial is an oft-cited mechanism for shielding remains from degradation, but not all fossils fit nicely into this paradigm. Dinosaurian mummies in particular seemingly require two mutually exclusive taphonomic processes to preserve under that framework: desiccation and rapid burial. Here we present a recently prepared Edmontosaurus mummy that reveals an alternate fossilization pathway for resistant soft tissues (e.g., skin and nails). While the skin on this specimen is well-preserved in three dimensions and contains biomarkers, it is deflated and marked by the first documented examples of injuries consistent with carnivore activity on dinosaurian soft tissue during the perimortem interval. Incomplete scavenging of the carcass provided a route for the gases, fluids, and microbes associated with decomposition to escape, allowing more durable soft tissues to persist through the weeks to months required for desiccation prior to entombment and fossilization. This pathway is consistent with actualistic observations and explains why dinosaurian skin, while rare, is more commonly preserved than expected if extreme circumstances were required for its preservation. More broadly, our assumptions guide specimen collection and research, and the presence of soft tissues and biomolecules in fossils that demonstrably were not rapidly buried, such as this mummy, suggests that such types of evidence may be substantially more common than previously assumed.
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... In reptiles, scales may not regrow, leaving a central region of the smooth dermis that may be surrounded by a disrupted region of small, irregular scales that differ from the surrounding 'normal' scales [23,24]. Trauma-induced granulation tissue surrounded by a ring of disrupted scales has been reported in the skin of at least one dinosaur [26], but none of these characteristic features are observable in SMF R 4970. ...
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Background In egg-laying amniotes, the developing embryo is tethered to a number of the extraembryonic membranes including the yolk sac and allantois that deliver oxygen and nutrients and remove metabolic waste products throughout embryonic development. Prior to, or soon after hatching, these membranes detach from the animal leaving a temporary or permanent umbilical scar (umbilicus) equivalent to the navel or ‘belly button’ in some placental mammals, including humans. Although ubiquitous in modern mammals and reptiles (including birds), at least early in their ontogeny, the umbilicus has not been identified in any pre-Cenozoic amniote. Results We report the oldest preserved umbilicus in a fossil amniote from a ~130-million-year-old early-branching ceratopsian dinosaur, Psittacosaurus . Under laser-stimulated fluorescence (LSF), the umbilicus is revealed as an elongate midline structure delimited by a row of paired scales on the abdomen. The relatively late ontogenetic stage (close to sexual maturity) estimated for the individual indicates that the umbilicus was probably retained throughout life. Conclusions Unlike most extant reptiles and birds that lose this scar within days to weeks after hatching, the umbilicus of Psittacosaurus persisted at least until sexual maturity, similar to some lizards and crocodylians with which it shares the closest morphological resemblance. This discovery is the oldest record of an amniote umbilicus and the first in a non-avian dinosaur. However, given the variability of this structure in extant reptilian analogues, a persistent umbilical scar may not have been present in all non-avian dinosaurs.
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... Lampreys (Petromyzontidae) rip deeper wounds upon attachment, however, the scars in question appear to be very flat and superficial and sometimes do not affect the surrounding skin. On the other hand, healed wounds can show similar structures, as is reported from fossil examples (Rothschild and Depalma, 2013). Given the unordered arrangement and sometimes irregular shape of the structures in question, however, no gnathostome producer of potentially healed bitemarks is considered likely at this time. ...
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... [26]), investigating, inter alia, isolated bone elements showing obvious pathologies, preserved neoplasms in the fossil record, predator-prey interactions and ethology, etc. (e.g. [27,29,64,68,[95][96][97][98][99][100][101][102][103][104][105][106]). More generally, few papers combine macroscopic, radiographic and histological approaches for complete differential diagnostic (e.g. ...
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... Dinosaur fossils often display evidence of injuries that can be attributed to accidents, old age, predation attempts, intraspecific combat, or metabolic disorders (e.g. Carpenter, 2000;Currie, 2000;Wolff et al., 2009;Rothschild and Depalma, 2013;Foth et al., 2015;Gonzalez et al., 2017;). The specimen being reviewed is a 150 million-year-old Allosaurus fragilis, MOR 693, from the Upper Jurassic Morrison Formation of Big Horn County, Wyoming. ...
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Palaeopathology is important as it provides remarkable insights into the lifestyles of dinosaurs and other prehistoric animals. The Late Jurassic Allosaurus known as Big Al (MOR 693) from Big Horn County, Wyoming preserves at least 19 injuries. About 2% of all bones showed abnormalities, including osteomyelitis on the right foot, on the first phalanx of the third toe, which may have contributed to the animal's death. There would likely have been many more pathologies that did not make it into the paleontological record due do the lack of soft-tissue preservation. Analysis of MOR 693's immune response to bone infections and comparing it to other theropods, we can confidently say that dinosaurs possessed an immune system that isolated and localized infections like extant Aves. Institution Abbreviations MOR, Museum of the Rockies; UUVP, University of Utah Vertebrate Paleontology
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... 210 HU total average values, obtained from different cross-sections slices passing through 211 the putative injured area (Fig. 4a, shell deformations can be also attributed to congenital phenomena (e.g. absence of bone 234 element, conjoined or parasitic twin, see Rothschild et al., 2013). 235 ...
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Comparative cranial biomechanics reveal that Late Cretaceous tyrannosaurids exerted relatively greater bite force than in early‐diverging tyrannosauroids
Article
Full-text available
  • Sep 2023
Tyrannosaurus has been an exemplar organism in feeding biomechanical analyses. An adult Tyrannosaurus could exert a bone‐splintering bite force, through expanded jaw muscles and a robust skull and teeth. While feeding function of adult Tyrannosaurus has been thoroughly studied, such analyses have yet to expand to other tyrannosauroids, especially early‐diverging tyrannosauroids ( Dilong, Proceratosaurus , and Yutyrannus ). In our analysis, we broadly assessed the cranial and feeding performance of tyrannosauroids at varying body sizes. Our sample size included small ( Proceratosaurus and Dilong ), medium‐sized ( Teratophoneus ), and large ( Tarbosaurus, Daspletosaurus , Gorgosaurus , and Yutyrannus ) tyrannosauroids, and incorporation of tyrannosaurines at different ontogenetic stages (small juvenile Tarbosaurus, Raptorex , and mid‐sized juvenile Tyrannosaurus ). We used jaw muscle force calculations and finite element analysis to comprehend the cranial performance of our tyrannosauroids. Scaled subtemporal fenestrae areas and calculated jaw muscle forces show that broad‐skulled tyrannosaurines ( Tyrannosaurus , Daspletosaurus , juvenile Tyrannosaurus , and Raptorex ) exhibited higher jaw muscle forces than other similarly sized tyrannosauroids ( Gorgosaurus, Yutyrannus , and Proceratosaurus ). The large proceratosaurid Yutyrannus exhibited lower cranial stress than most adult tyrannosaurids. This suggests that cranial structural adaptations of large tyrannosaurids maintained adequate safety factors at greater bite force, but their robust crania did not notably decrease bone stress. Similarly, juvenile tyrannosaurines experienced greater cranial stress than similarly‐sized earlier tyrannosauroids, consistent with greater adductor muscle forces in the juveniles, and with crania no more robust than in their small adult predecessors. As adult tyrannosauroid body size increased, so too did relative jaw muscle forces manifested even in juveniles of giant adults.
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Morphology and distribution of scales, dermal ossifications, and other non-feather integumentary structures in non-avialan theropod dinosaurs
Article
  • Jan 2022
  • BIOL REV
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.
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The pathophysiologic basis for wound healing and cutaneous regeneration
Chapter
  • Dec 2009
In this chapter, essential aspects of cutaneous wound repair/scar formation, including the early response and the cellular phase, will be covered. Fundamental differences between wound repair and regeneration, with emphasis on fibroblast and endothelial cell contribution to respective dermal architecture, will be discussed. 'Essential ingredients' for cutaneous regeneration will be explored in detail. Lastly, issues regarding stem cells, progenitors and cellular 'plasticity', as they relate to cutaneous wound healing, will be examined.
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Dinosaur Paleoecology
Chapter
  • Jun 2004
This chapter discusses the paleoecology of dinosaurs. It first examines the variety of adaptations of dinosaurs to sustain their herbivorous habits. It then describes Mesozoic paleobotany and outlines the coevolution between dinosaurs and plants. During the Late Triassic, there was the coincident rise of conifers and the appearance of prosauropods, large-bodied dinosaurs potentially capable of reaching higher than any herbivore that had preceded them. The Middle Jurassic was a key time in the evolution of dinosaur herbivory, for it was during this time that a number of groups of ornithischian herbivores must have arisen, including stegosaurs, ankylosaurs, and some ornithopods. The chapter also examines the paleoecology of dinosaur carnivory and provides examples of paleoecological reconstructions of dinosaur-bearing ecosystems.
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