Christophe HendrickxNational Scientific and Technical Research Council | conicet · Unidad Ejecutora Lillo
Christophe Hendrickx
PhD
Hic sunt dracones
About
82
Publications
78,974
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
841
Citations
Citations since 2017
Introduction
I'm a postdoctoral fellow at the Unidad Ejecutora de Lillo in San Miguel de Tucuman, Argentina, working on the evolution of the dentition in theropod dinosaurs and non-mammalian cynodonts. My research interest also includes the feeding ecology of theropods and gomphodont cynodonts, the scaly skin of dinosaurs, and the identification of isolated theropod teeth.
Additional affiliations
April 2019 - April 2021
October 2015 - December 2018
February 2010 - February 2015
Education
April 2019 - April 2021
October 2015 - December 2018
February 2010 - February 2015
Publications
Publications (82)
Theropod teeth are typically not described in detail, yet these abundant vertebrate fossils are not only frequently reported in the literature, but also preserve extensive anatomical information. Often in descriptions, important characters of the crown and ornamentations are omitted, and in many instances, authors do not include a description of th...
Gomphodont cynodonts were close relatives of mammals and one of the Mesozoic lineages of cynodont therapsids that became extinct at the end of the Triassic. Gomphodonts were omnivorous to herbivorous animals characterized by labiolingually expanded postcanines, which allowed tooth-to-tooth occlusion. The morphology of the upper and lower postcanine...
Isolated theropod teeth are some of the most common fossils in the dinosaur fossil record and are continually reported in the literature. Recently developed quantitative methods have improved our ability to test the affinities of isolated teeth in a repeatable framework. But in most studies, teeth are diagnosed on qualitative characters. This can b...
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 m...
The Frankfurt specimen of the early-branching ceratopsian dinosaur Psittacosaurus is remarkable for the exquisite preservation of squamous (scaly) skin and other soft tissues that cover almost its entire body. Newly detected details revealed under Laser-Stimulated Fluorescence (LSF) reveals the complexity of the squamous skin of Psittacosaurus , in...
Middle Jurassic theropods have a scanty record worldwide, especially from Gondwana. In India, where Jurassic theropods are particularly rare and only represented by a few isolated teeth and some badly preserved bones, there is currently no record of theropods from the Middle Jurassic of western India. Here we report the first theropod dental materi...
The Frankfurt specimen of the early-branching ceratopsian dinosaur Psittacosaurus is remarkable for the exquisite preservation of squamous (scaly) skin and other soft tissues that cover almost its entire body. New observations under Laser-Stimulated Fluorescence (LSF) reveal the complexity of the squamous skin of Psittacosaurus, including several u...
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...
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 preserve...
A partial skull (BP/1/7976) of a very large cynodont from the Middle Triassic Cynognathus Assemblage Zone (Cricodon-Ufudocyclops subzone) of South Africa is described. The specimen represents a new gomphodont taxon, Impidens hancoxi, gen. et sp. nov., diagnosed by five sectorial teeth constituting just over half of the length of the upper postcanin...
The discovery of theropod shed teeth associated with sauropod remains is relatively common in Cretaceous deposits of Patagonia. However, only a handful of studies have thoroughly explored the phylogenetic affinities of the theropod dental material. Here, we describe and identify twelve theropod shed teeth associated with a partially complete skelet...
Epidermal scales among modern reptiles are morphologically diverse and serve a variety of functions ranging from moisture balance to chemoreception. Despite being predominantly squamous-skinned (scaly), the functional implications of this type of integument have never before been explored for a dinosaur. Re-examination of the holotype of the therop...
Our knowledge of the reproductive biology of dinosaurs covers a range of aspects, from brooding behaviour to nesting style and the timing of sexual maturity. Yet, the basic anatomy and function of the cloaca in non-avialan dinosaurs remains unknown. Here, we describe the outer morphology of the only known non-avialan dinosaur cloaca, preserved in a...
Early in amniote evolution, epidermal scales evolved in stem reptiles as an efficient barrier against water loss and ultraviolet radiation, making them a key development in the transition to a fully terrestrial existence [ 1
• Lillywhite H.B.
• Maderson P.F.A.
Skin structure and permeability. Biol. Reptilia. 1982; 12 : 397-442
• Google Scholar...
We here present a new gomphodont cynodont from the Ladinian/Carnian Upper Omingonde Formation of central Namibia. Etjoia dentitransitus gen. et sp. nov. is a medium-sized (skull length of 88.5 mm) omnivorous gomphodont represented by an almost complete skull and a few cervical vertebrae. This new taxon is diagnosed by divergent first left and right...
If we imagine walking through Mesozoic lands, we would be able to observe vertebrates with peculiar combinations of morphological traits, some of which would seem to be intermediary to animals seen today. We would witness a terrestrial vertebrate fauna dominated by dinosaurs of various sizes and diversity, accompanied by many other animal groups th...
The gross dental morphology of the holotype of the theropod Sinraptor dongi from the Jurassic Shishugou Formation of China is comprehensively described. We highlight a combination of dental features that appear to be restricted to Sinraptor: i) crowns with denticulated mesial and distal carinae extending from the root, and an irregular surface text...
The Middle Jurassic is a largely mysterious interval in dinosaur evolution, as few fossils of this age are known worldwide. In recent years, the Isle of Skye has yielded a substantial record of trackways, and a more limited inventory of body fossils, that indicate a diverse fauna of Middle Jurassic dinosaurs living in and around lagoons and deltas....
Cricodon metabolus is a trirachodontid cynodont from the Anisian (Middle Triassic) of eastern and southern Africa. It has labiolingually expanded (gomphodont) postcanines but also a sectorial tooth in the last postcanine locus. In this paper, we examine the crown microstructure of isolated sectorial and gomphodont postcanines belonging to the holot...
In their recent publication on an overview of theropod discoveries and classification, Hendrickx and colleagues mistakenly attributed the earliest historical reports of nonavian theropods in North America and South America to Joseph Leidy in 1856 and Florentino Ameghino in 1899, respectively. Yet, theropod tracks from Massachusetts had already been...
Six quadrate bones, of which two almost certainly come from the Kem Kem beds (Cenomanian, Upper Cretaceous) of south-eastern Morocco, are determined to be from juvenile and adult individuals of Spinosaurinae based on phylogenetic, geometric morphometric, and phylogenetic morphometric analyses. Their morphology indicates two morphotypes evidencing t...
Institutional abbreviations, comments on Cristatusaurus lapparenti (Figs A and B in S1 File), illustration of MHNM.KK377 and.KK378 (Fig C in S1 File), geological settings of the Kem Kem beds, quadrate-based diagnosis of a new species of Spinosaurinae tentatively referred to Sigilmassasaurus brevicollis, quadrate-based characters, list of taxa inclu...
The quadrate of reptiles and most other tetrapods plays an important morphofunctional role by allowing the articulation of the mandible with the cranium. In Theropoda, the morphology of the quadrate is particularly complex and varies importantly among different clades of non-avian theropods, therefore conferring a strong taxonomic potential. Incons...
Theropod teeth are particularly abundant in the fossil record and frequently reported in the literature. Yet, the dentition of many theropods has not been described comprehensively, omitting details on the denticle shape, crown ornamentations and enamel texture. This paucity of information has been particularly striking in basal clades, thus making...
Theropods form a taxonomically and morphologically diverse group of dinosaurs that include extant birds. Inferred relationships between theropod clades are complex and have changed dramatically over the past thirty years with the emergence of cladistic techniques. Here, we present a brief historical perspective of theropod discoveries and classific...
The skull-bone quadrate in nonavian theropods is very diverse morphologically alongside the disparity of the group as a whole. However this disparity has been underestimated for taxonomic purposes. In order to evaluate the phylogenetic potential and investigate the evolutionary transformations of the quadrate, we conducted a Catalano-Goloboff phylo...
The skull-bone quadrate in nonavian theropods is very diverse morphologically alongside the disparity of the group as a whole. However this disparity has been underestimated for taxonomic purposes. In order to evaluate the phylogenetic potential and investigate the evolutionary transformations of the quadrate, we conducted a Catalano-Goloboff phylo...
The skull-bone quadrate in nonavian theropods is very diverse morphologically alongside the disparity of the group as a whole. However this disparity has been underestimated for taxonomic purposes. In order to evaluate the phylogenetic potential and investigate the evolutionary transformations of the quadrate, we conducted a Catalano-Goloboff phylo...
By allowing the articulation of the mandible with the cranium, the quadrate of diapsids and most other tetrapods plays an important role morphofunctionally. In Theropoda, its morphology is particularly complex and varies importantly among different clades of nonavian theropods so that the quadrate possesses a strong taxonomic potential. Inconsisten...
The Lourinhã Formation (Kimmeridgian-Tithonian) of Central West Portugal is well known for its diversified dinosaur fauna similar to that of the Morrison Formation of North America; both areas share dinosaur taxa including the top predator Torvosaurus, reported in Portugal. The material assigned to the Portuguese T. tanneri, consisting of a right m...
Theropod dinosaurs form a highly diversified clade, and their teeth are some of the most common components of the Mesozoic dinosaur fossil record. This is the case in the Lourinhã Formation (Late Jurassic, Kimmeridgian-Tithonian) of Portugal, where theropod teeth are particularly abundant and diverse. Four isolated theropod teeth are here described...
A clutch of crushed eggs and embryonic material ascribed to the megalosaurid theropod Torvosaurus, a primitive carnivorous bipedal dinosaur, has been discovered in the Lourinhã Formation in Portugal. The find represents the only unequivocal evidence of early theropod embryos discovered to date, furthering our understanding of dinosaur eggshell morp...
The non-avian saurischians that have associated eggshells and embryos are represented only by the sauropodomorph Massospondylus and Coelurosauria (derived theropods), thus missing the basal theropod representatives. We report a dinosaur clutch containing several crushed eggs and embryonic material ascribed to the megalosaurid theropod Torvosaurus....
Radial section of the tomography of ML1188 eggshells
Supplementary Notes
Transverse section of the tomography of ML1188 eggshells
Questions
Question (1)
Hi everyone,
I wish to measure the curvature of both mesial and distal profiles of the tooth crown in different theropod taxa and along the tooth row based on photos. Is there a simple way to quantify the curvature of an object like a tooth or a beak by using an image processing program such as ImageJ?
I tried to use the curve fitter option based on the X and Y coordinates of a series of points placed along the profile with ImageJ but the result is totally incoherent the moment the profile is not correctly oriented. Furthermore, I wish to have different values for convex and concave profiles (one would be negative while the other would be positive) and ImageJ does not seem to take this into consideration.
Would anyone know whether there is an image processing program that could provide the degree of curvature of a profile based on a series of points? And if yes, what is the most straightforward and simplest method to do so?
Ma