Koen Stein

Royal Belgian Institute of Natural Sciences · Direction Public Services

We present novel findings on sauropod bone histology that cast doubt on general palaeohistological concepts concerning the true nature of woven bone in primary cortical bone and its role in the rapid growth and giant body sizes of sauropod dinosaurs. By preparing and investigating longitudinal thin sections of sauropod long bones, of which transver...

Fossil dinosaur embryos are surprisingly rare, being almost entirely restricted to Upper Cretaceous strata that record the late stages of non-avian dinosaur evolution. Notable exceptions are the oldest known embryos from the Early Jurassic South African sauropodomorph Massospondylus and Late Jurassic embryos of a theropod from Portugal. The fact th...

Sauropods were the largest terrestrial tetrapods (>10(5) kg) in Earth's history and grew at rates that rival those of extant mammals. Magyarosaurus dacus, a titanosaurian sauropod from the Upper Cretaceous (Maastrichtian) of Romania, is known exclusively from small individuals (<10(3) kg) and conflicts with the idea that all sauropods were massive....

Derived ornithopods, such as hadrosaurids, show a high occurrence of fossilized lesions and diseases. However, paleopathologies in iguanodontians seem to be less common, considering the rich fossil record of these taxa in Europe, in particular in Belgium, Britain and Spain. Here, we describe an iguanodontian femur discovered in England that exhibit...

The Kem Kem Group of Southeastern Morocco, North Africa, is well known for theropod remains, especially isolated teeth. Here, a collection of isolated theropod teeth is assessed for diversity using a combination of linear discriminant, phylogenetic, and machine learning analyses for the first time. The results confirm earlier studies on Kem Kem the...

The Vegagete rhabdodontomorph is an as-yet unnamed ornithopod known from tiny and fragmentary remains, and was collected in the upper Barremian – lower Aptian of the Salas de los Infantes municipality (Burgos Province, Spain). As the earliest known rhabdodontomorph and a stem member of the lineage leading to Rhabdodontidae, this animal is key to be...

The Cretaceous–Palaeogene mass extinction around 66 million years ago was triggered by the Chicxulub asteroid impact on the present-day Yucatán Peninsula1,2. This event caused the highly selective extinction that eliminated about 76% of species3,4, including all non-avian dinosaurs, pterosaurs, ammonites, rudists and most marine reptiles. The timin...

Remains of Garrigatitan meridionalis nov. gen. et sp. were found in two bonebeds of sequence 2 from the upper Campanian site of Velaux-La Bastide Neuve (Aix-en-Provence Basin, Bouches du Rhône department). The vertebrate assemblage is dominated by dinosaurs, including the titanosaur Atsinganosaurus velauciensis. Garrigatitan meridionalis presents t...

Histologic studies of paleopathologies of basal sauropod humeri: cf. Isanosaurus (Early to Late Jurassic, Thailand) and Spinophorosaurus nigerensis (Early to Middle Jurassic, Niger). Radial fibrolamellar bone (RFB) has been observed for both specimens in their humeri cortex, that were interpreted as spiculated periosteal both specimens. The indivi...

Geochemical research was conducted on the remains of the Suermont quarry in Moresnet. Between 2017 and 2019 around 300 samples of the uppermost Famennian formation of Evieux were studied and used un geochemical analysis to see if the famous Zn and Pb deposits from the younger Dinantian (Lower - Carboniferous) could also be found in the underlying D...

The histology of sauropod long bones often appears uniform and conservative along their evolutionary tree. One of the main aspects of their bone histology is to exhibit a fibrolamellar complex in the cortex of their long bones. Here, we report another bone tissue, the radial fibrolamellar bone (RFB), in the outer cortex of the humeri of a young adu...

Het dorp Moresnet, nabij het drielandenpunt (België, Nederland en Duitsland), kende de afgelopen eeuwen een turbulente, maar fascinerende geschiedenis. Naast deze historische significantie is dit dorp ook binnen een aardwetenschappelijke context niet geheel onbesproken. Gedurende vele decennia hebben de intensieve ontginning van lood- en zinkertsen...

one of the fossil record's most puzzling features is the absence of preserved eggs or eggshell for the first third of the known 315 million year history of amniote evolution. Our meagre understanding of the origin and evolution of calcareous eggshell and amniotic eggs in general, is largely based on Middle Jurassic to Late Cretaceous fossils. For d...

ABSTRACT: The derived sauropod clade Titanosauria encompasses the largest land animals that ever roamed the Earth as well as dwarfed species that evolved in restricted, insular habitats. Here, we report on the long bone histology (humeri and femora) of several mature individuals belonging to a new, small-sized titanosaur from the Upper Cretaceous o...

Vertebrate hard tissues consist of mineral crystallites within a proteinaceous scaffold that normally degrades post-mortem. Here we show, however, that decalcification of Mesozoic hard tissues preserved in oxidative settings releases brownish stained extracellular matrix, cells, blood vessels, and nerve projections. Raman Microspectroscopy shows th...

ABSTRACT: The histology of the long bone of sauropods appears uniform and conservative along the Sauropoda evolutionary tree. One of the main aspects of their bone histology is to exhibit a Fibrolamellar Complex (FLC) with circumferential vascularization in the cortex of their long bones. However, we report Radial Fibrolamellar bone (RFB) in the ou...

ABSTRACT: Titanosaurian sauropods include the largest land animals that ever walked on Earth. However, some of them evolved into dwarfed species, linked to their insular habitats. Here, we report on the long bone histology of several mature individuals of the small-sized titanosaur Atsinganosaurus velauciensis from the Upper Cretaceous of Velaux –...

The Upper Cretaceous site of Velaux-La Bastide Neuve (Bouches-du-Rhône Department, France) is well-known for its dinosaur specimens, more specifically the titanosaurian remains. The taxon Atsinganosaurus velauciensis is represented by several partially articulated skeletons found in this upper Campanian site; some of this material was described by...

New remains of the titanosaurian sauropod Atsinganosaurus velauciensis from its Upper Cretaceous type horizon and type locality in Velaux-La Bastide Neuve (Bouches-du-Rhône Department, Provence) in southern France are described. This locality is considered to be upper Campanian (Argiles et Grès à Reptiles Formation, Aix-en-Provence Basin). The new...

Squamate reptiles constitute a major component of the world’s terrestrial vertebrate diversity, encompassing many morphotypes related to ecological specialization. Specifically, Gekkota, the sister clade to most other squamates, have highly specialized autopodia, which have been linked to their ecological plasticity. In this study, a developmental...

Maniraptora includes birds and their closest relatives among theropod dinosaurs. During the Cretaceous period, several maniraptoran lineages diverged from the ancestral coelurosaurian bauplan and evolved novel ecomorphologies, including active flight, gigantism, cursoriality and herbivory. Propagation X-ray phase-contrast synchrotron microtomograph...

Rhabdodontidae is a successful clade of ornithopod dinosaurs, characteristic of Late Cretaceous continental faunas in Europe. A new rhabdodontid from the late Campanian, of southern France, Matheronodon provincialis gen. et sp. nov., is characterized by the extreme enlargement of both its maxillary and dentary teeth, correlated to a drastic reducti...

The Late Cretaceous of southwestern Europe (the Ibero-Armorican Island) is full of fossil-sites with titanosaurian remains, especially the Center-North of the Iberian Peninsula and southeastern France. The titanosaurian diversity is updated to at least four taxa: Lirainosaurus and Lohuecotitan from Spain, Ampelosaurus and Atsinganosaurus from Franc...

As a result of several years of screen-washing activity, a remarkable assemblage of eggshell fragments has been recovered from the Late Cretaceous vertebrate locality of Iharkút, Hungary. Detailed investigation of the assemblage by multiple visualization techniques (scanning electron microscopy, polarizing light microscopy, X-ray micro-computed tom...

ABSTRACT: The detailed study of fossil dinosaur eggshells from Upper Cretaceous continental deposits from the Haţeg Basin (Romania), the Arc Basin and Argentina and from the Thanetian of the Rians Basin (France) was made in order to test the robustness of fossil eggs' parataxonomy and to reveal novel data on dinosaur palaeobiology. µXRF, XRD and ca...

Sauropod bone histology has provided a great deal of insight into the life history of these enormous animals. However, because of high growth rates, annual growth rings are not common in sauropod long bones, so directly measuring growth rates and determining sexual maturity require alternative measures. Histological ontogenetic stages (HOS) have be...

Many recent studies using next generation technologies to unravel exceptional molecular preservation have changed our view on the limits of biomolecular stability during fossilization. Nevertheless, common hard tissues have not attracted much attention. Thus, the color change of vertebrate hard tissues from in vivo white to blackish-brown in many f...

The Late Cretaceous Nemegt Formation, Gobi Desert, Mongolia has already yielded abundant and complete skeletons of the hadrosaur Saurolophus angustirostris, from half-grown to adult individuals. Methodology/Principal Findings: Herein we describe perinatal specimens of Saurolophus angustirostris, associated with fragmentary eggshell fragments. The s...

Kokartus honorarius from the Middle Jurassic (Bathonian) of Kyrgyzstan is one of the oldest salamanders in the fossil record, characterized by a mixture of plesiomorphic morphological features and characters shared with crown-group salamanders. Here we present a detailed histological analysis of its long bones. The analysis of a growth series demon...

Medullary bone is a special bone tissue forming on the endosteal surface of the medullary cavity in the bones of female birds prior to and during egg-laying to serve as a calcium reservoir for building the hard eggshell. It has also been identified in non-avian dinosaurs, where its presence is considered as a reliable indicator of a sexually mature...

Research on the bone histology of extant and extinct animals has a long scientific history and an accurate description of microstructural tissues is the cornerstone of the field. Ideally, terminology needs to convey as much information as possible about the structural, developmental, and functional aspects of bone tissues corresponding to the up-to...

Osteocytes harbour much potential for paleobiological studies. Synchrotron radiation and spectroscopic analyses are providing fascinating data on osteocyte density, size and orientation in fossil taxa. However, such studies may be costly and time consuming. Here we describe an uncomplicated and inexpensive method to measure osteocyte lacunar densit...

Laminar bone tissue is commonly found in Dinosauria (including birds) and Mammalia. The tissue emerged convergently several times, and its frequent recurrence among amniotes has stimulated researchers to study some of its geometric features. One such feature is lamina thickness or lamina density (LD, expressed as number of laminae per mm. We measur...

To study the evolution of growth rates, it is necessary to develop two things: a sense of the ontogenetic patterns of individual species, and a phylogeny of the spe- cies in question. Studying ontogenies in phylogenetic context is the best approach to understanding how growth rates evolve.

The microscopic examination of fossilized bone tissue is a sophisticated and increasingly important analytical tool for understanding the life history of ancient organisms. This book provides an essential primer and manual for using fossil bone histology to investigate the biology of extinct tetrapods. Twelve experts summarize advances in the field...

The Briar Creek Bonebed (Artinskian, Nocona Formation) in Archer County is one of the richest sources of Dimetrodon bones in the Lower Permian of Texas, USA. Based on size, a small (D. natalis), an intermediate (D. booneorum), and a large species (D. limbatus) have been described from this locality. It has been proposed that these traditionally rec...

Long bone histology of the most derived Sauropoda, the Titanosauria suggests that titanosaurian long bone histology differs from the uniform bone histology of basal Sauropoda. Here we describe the long bone histology of the titanosaur Ampelosaurus atacis and compare it to that of basal neosauropods and other titanosaurs to clarify if a special tita...

Histological description of sampled bones of Ampelosaurus atacis from Bellevue locality (MDE C3) and the titanosaurs from north of Narbonne (Cru). The bones are listed by midshaft circumference (see Table 1). Abbreviations: FLB = fibrolamellar bone tissue; ic = inner cortex; lb = lamellar bone matrix; mc = medullary cavity; oc = outer cortex; pfb =...

Rhamphorhynchus from the Solnhofen Limestones is the most prevalent long tailed pterosaur with a debated life history. Whereas morphological studies suggested a slow crocodile-like growth strategy and superprecocial volant hatchlings, the only histological study hitherto conducted on Rhamphorhynchus concluded a relatively high growth rate for the g...

Explanatory drawing of the method used for wingspan estimations. The skeletal reconstruction of the wing spar of Rhamphorhynchus with fully extended wings is based on the ‘Darkwing’ specimen (after Prondvai and Hone, 2008). (TIF)

Dimensional differences between the investigated Rhamphorhynchus specimens based on the wingspan estimates. Note that the wingspan of the largest specimen BSPG 1929 I 69 is five times of that of the smallest specimen BSPG 1960 I 470a. (TIF)

List of 17 Rhamphorhynchus specimens used to reveal the relationship between femoral length and estimated wingspan. Boldface type marks the histologically investigated specimens. (TIF)

Institutional abbreviations appearing in the inventor numbers of specimens. (DOC)

Abbreviations for histological structures used in the figures. (DOC)

Bone histology has emerged as the major source of information on life history of dinosaurs, and sauropodomorphs are one of the best sampled clades. The large long bones (humerus and femur) preserve the most complete growth record, which allows inference on life history, thermometabolism, and other aspects of sauropod biology. Basal sauropodomorphs...

Islands are fascinating natural laboratories of evolution. One much debated theme among evolutionary ecologists is whether there is an ‘island rule’, the observation that large animals tend to become smaller and small animals larger. Franz Nopcsa was the first, in 1914, to suggest that the latest Cretaceous dinosaurs from Haţeg, Romania were an isl...

Sauropodomorph dinosaurs include the largest land animals to have ever lived, some reaching up to 10 times the mass of an African elephant. Despite their status defining the upper range for body size in land animals, it remains unknown whether sauropodomorphs evolved larger-sized genomes than non-avian theropods, their sister taxon, or whether a re...

This paper describes a new method for obtaining histological core samples. The Histological Coring Method (HCM) involves drilling a small core at a standardized location on the bone chosen for study. The core is collected using diamond studded drill bits mounted on a standard household power drill. The drill is stabilized in a drill press to contro...

  The Kuehneosauridae (Late Triassic, Britain, USA) had remarkable adaptations, most notably their elongate mid-dorsal ribs that were presumably covered with a skin membrane in life. These lateral ‘wings’ have always been linked with some form of gliding adaptation, but quantitative studies have been limited. Here, we provide a thorough aerodynamic...