Darla Karen Zelenitsky

Darla Karen Zelenitsky
The University of Calgary | HBI · Department of Geoscience

M.Sc., Ph.D.

About

79
Publications
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Publications

Publications (79)
Article
Full-text available
Despite the discovery of many dinosaur eggs and nests over the past 100 years, articulated in-ovo embryos are remarkably rare. Here we report an exceptionally preserved, articulated oviraptorid embryo inside an elongatoolithid egg, from the Late Cretaceous Hekou Formation of southern China. The head lies ventral to the body, with the feet on either...
Article
The albertosaurines Albertosaurus sarcophagus and Gorgosaurus libratus are among the best represented tyrannosaurids, known from nearly complete growth series. These specimens provide an opportunity to study mandibular biomechanical properties and tooth morphology in order to infer changes in feeding behavior and bite force through ontogeny in tyra...
Article
Full-text available
Carcharodontosauria is a group of medium to large-sized predatory theropods, distributed worldwide during the Cretaceous. These theropods were probably the apex predators of Asiamerica in the early Late Cretaceous prior to the ascent of tyrannosaurids, although few Laurasian species are known from this time due to a poor rock record. Here, we descr...
Article
Turtle eggs containing embryos are exceedingly rare in the fossil record. Here, we provide the first description and taxonomic identification, to our knowledge, of a fossilized embryonic turtle preserved in an egg, a fossil recovered from the Upper Cretaceous Xiaguan Formation of Henan Province, China. The specimen is attributed to the Nanhsiungche...
Article
Full-text available
Calcified eggshells protect developing embryos against environmental stress and contribute to reproductive success¹. As modern crocodilians and birds lay hard-shelled eggs, this eggshell type has been inferred for non-avian dinosaurs. Known dinosaur eggshells are characterized by an innermost membrane, an overlying protein matrix containing calcite...
Article
Upper Cretaceous tyrannosauroid material from North America was primarily known from upper Campanian through Maastrichtian formations until the recent discovery of derived tyrannosaurid taxa from lower-to-mid Campanian deposits in the southwestern United States. However, diagnostic material from contemporaneous deposits further north in Alberta (Ca...
Article
The Kamitaki Locality in the Albian Ohyamashimo Formation in the eastern Hyogo Prefecture of southwestern Japan is among the richest Lower Cretaceous fossil egg sites in the world. So far, eggshells of five different ootaxa, one ornithopod and four theropods, have been identified from the Kamitaki Bonebed Quarry. Although previous discoveries of eg...
Article
Full-text available
Studying the origin of avian thermoregulation is complicated by a lack of reliable methods for measuring body temperatures in extinct dinosaurs. Evidence from bone histology and stableisotopes often relies on uncertain assumptions about the relationship between growth rate and body temperature, or the isotopic composition (δ ¹⁸ O) of body water. Cl...
Article
Full-text available
Daspletosaurus is a large tyrannosaurine found in upper Campanian deposits of Alberta and Montana. Although several large subadult and adult individuals of this taxon are known, only one juvenile individual, TMP 1994.143.1, has been identified. This specimen has played a key role in the idea that juvenile tyrannosaurid individuals are difficult to...
Article
Colonial nesting behavior has been inferred in a variety of non-avian dinosaurs based on high concentrations of nests preserved in an area, but sedimentologic and taphonomic evidence demonstrating the contemporaneity of the nests is often lacking. A new nesting site discovered in the Upper Cretaceous Javkhlant Formation of the eastern Gobi Desert,...
Article
Three juvenile specimens of Prosaurolophus maximus, represented by articulated to disarticulated skeletons, are the smallest known individuals for the taxon. Cranial anatomy of the juvenile specimens indicates that diagnostic characters of P. maximus are ontogenetically variable. In the smallest individual, the crest and deeply excavated fossa at t...
Article
Full-text available
A single block containing five articulated osteoglossomorphs was recovered from the Paskapoo Formation of southern Alberta, during development of a residential community in Calgary. Two of the specimens represent a new species of Joffrichthys, and the other three represent a new genus and species of osteoglossomorph. The discovery of a new species...
Article
Most birds sit on their eggs during incubation, a behaviour that likely evolved among non-avian dinosaurs. Several 'brooding' specimens of smaller species of oviraptorosaurs and troodontids reveal these non-avian theropods sat on their eggs, although little is known of incubation behaviour in larger theropod species. Here we examine egg clutches ov...
Article
Full-text available
Dinosaurs thrived and reproduced in various regions worldwide, including the Arctic. In order to understand their nesting in diverse or extreme environments, the relationships between nests, nesting environments, and incubation methods in extant archosaurs were investigated. Statistical analyses reveal that species of extant covered nesters (i.e.,...
Article
Archosaurs (e.g., crocodilians, pterosaurs, and dinosaurs including birds) are the most diverse and successful clade of terrestrial vertebrates. An understanding of the nesting methods and behaviors of both extinct (e.g., non-avian dinosaurs) and extant archosaurs (i.e., crocodilians and birds) is crucial for the advancement of our understanding of...
Article
North America is known for its rich uppermost Cretaceous record of dinosaur egg remains, although a notable fossil gap exists during the lower Maastrichtian. Here we describe a diverse dinosaur eggshell assemblage from the St. Mary River Formation of southern Alberta that, in conjunction with recently described eggs from the same formation in Monta...
Conference Paper
Full-text available
The genus Joffrichthys was named based on articulated specimens recovered from Palaeocene sediments of the Paskapoo Formation from a road cut near Joffre Bridge Alberta. When the type species, J. symmetropterus, was described, it was placed in the subfamily Heterotinae of the Osteoglossidae. The extant members of Heterotinae are the South American...
Article
The North American fossil record of dinosaur eggshells for the Cretaceous is primarily restricted to formations of the middle (Albian–Cenomanian) and uppermost (Campanian–Maastrichtian) stages, with a large gap in the record for intermediate stages. Here we describe a dinosaur eggshell assemblage from a formation that represents an intermediate and...
Article
Full-text available
The abundance of dinosaur eggs in Upper Cretaceous strata of Henan Province, China led to the collection and export of countless such fossils. One of these specimens, recently repatriated to China, is a partial clutch of large dinosaur eggs (Macroelongatoolithus) with a closely associated small theropod skeleton. Here we identify the specimen as an...
Article
The abundance of dinosaur eggs in Upper Cretaceous strata of Henan Province, China led to the collection and export of countless such fossils. One of these specimens, recently repatriated to China, is a partial clutch of large dinosaur eggs (Macroelongatoolithus) with a closely associated small theropod skeleton. Here we identify the specimen as an...
Data
Supplementary Figures, Supplementary Tables, Supplementary Notes and Supplementary References
Article
The Willow Creek Formation (upper Maastrichtian – lower Paleocene) of southwestern Alberta is a poorly fossiliferous formation that preserves a low end-Cretaceous dinosaur diversity compared with most correlative terrestrial deposits in the North American Western Interior. Although only three dinosaur taxa are known from skeletal remains (Tyrannosa...
Article
Birds stand out from other egg-laying amniotes by producing relatively small numbers of large eggs with very short incubation periods (average 11-85 d). This aspect promotes high survivorship by limiting exposure to predation and environmental perturbation, allows for larger more fit young, and facilitates rapid attainment of adult size. Birds are...
Article
Mandibular force profiles apply the principles of beam theory to identify mandibular biomechanical properties that reflect the bite force and feeding strategies of extant and extinct predators. While this method uses external dimensions of the mandibular corpus to determine its biomechanical properties, more accurate results could potentially be ob...
Article
The Lower Cretaceous (Albian) Sasayama Group in the Hyogo Prefecture of southwestern Japan has yielded various vertebrate fossils, including skeletal remains of dinosaurs, anurans, lizards, and mammals, and recently eggshell fragments. Here we report on numerous fossil eggshells from the bone-bearing Kamitaki locality in Tamba City, which represent...
Article
Full-text available
Knowledge about the types of nests built by dinosaurs can provide insight into the evolution of nesting and reproductive behaviors among archosaurs. However, the low preservation potential of their nesting materials and nesting structures means that most information can only be gleaned indirectly through comparison with extant archosaurs. Two gener...
Article
Full-text available
Dinosaur tracksites recently discovered in exposures of the Belly River Group in the Milk River Natural Area (MRNA) and Dinosaur Provincial Park (DPP) of southern Alberta represent a novel type of ichnofossils. The tracks, all referable to hadrosaurs, occur as sideritic or calcareous concretions protruding above fine-grained deposits and are here t...
Article
Full-text available
A new Turonian amber occurrence, representing the oldest in situ amber locality in Australia and the southern-most locality in Gondwana, has recently been discovered in the Otway Basin of Victoria. The amber was collected from petroleum cores and many pieces contain a range of inclusions that can provide information on the depositional history of t...
Article
Estimates of water vapor conductance for the eggs (i.e., diffusive capacity of eggshell; Gh2o, mg H2O·day−1·Torr−1) of extinct archosaur species have been used to infer their nest type (i.e., covered vs. open) because experimental Gh2o values for living archosaur species appear to reflect nest type. The methods used to derive Gh2o for fossil eggs (...
Chapter
A bs t r ac t Hypacrosaurus stebingeri is known from one of the most complete ontogenetic series of dinosaurs, yet the adult skeletal material has never been fully described. Here, the first detailed description of all well-known H. stebingeri crania is presented, accompanied by the first multivariate statistical analysis for lambeosaurine crania t...
Chapter
A hadrosaur track site discovered in the Milk River Natural Area (MRNA) of southeastern Alberta represents the first dinosaur tracks reported from the Upper Cretaceous (late Campanian) Oldman Formation. The MRNA track site consists of a series of concretions exposed on top of fine-grained deposits, some recognizable as tridactyl pedal tracks. Seven...
Article
Nest humidity (Pnest) is important for archosaur incubation because it has a direct effect on the water vapour conductance () of the eggs. Estimates of are commonly used to infer nest type in extinct archosaurs, although it is unknown whether a relationship exists between nest type and nest humidity or between nest type and . In this study, the nes...
Article
Using tangential thin sections, we examined variation in porosity and water vapor conductance across two eggs of Troodon formosus, a small (similar to 50 kg) theropod dinosaur from the North American Upper Cretaceous, testing two hypotheses of egg incubation: (1) full burial within sediments or vegetation and (2) partial burial with exposed upper e...
Article
Pedogenic features and geochemical signatures of paleosol profiles exposed in the Horseshoe Canyon Formation (HCFm) were studied to reconstruct the ancient environments and climates that prevailed at high latitude (~ 60°N) in the North American Western Interior during the late Campanian to early Maastrichtian. Eight pedotypes representing hydromorp...
Article
Previously described feathered dinosaurs reveal a fascinating record of feather evolution, although substantial phylogenetic gaps remain. Here we report the occurrence of feathers in ornithomimosaurs, a clade of non-maniraptoran theropods for which fossilized feathers were previously unknown. The Ornithomimus specimens, recovered from Upper Cretace...
Article
The Zhutian and Dafeng formations (Upper Cretaceous) of the Heyuan Basin in northeastern Guangdong Province, China, have produced thousands of dinosaur eggs. Macromorphological features (egg diameter, egg shape, outer surface texture, and shell thickness) of 461 eggs were analyzed using non‐destructive techniques and subjected to statistical analys...
Article
A clutch of 12 eggs and numerous eggshell fragments recovered from the Oldman Formation at Devil's Coulee, southern Alberta, are described as Prismatoolithus levis oosp.nov. The eggs are elongate with a smooth outer surface and an eggshell structure that is referable to the angustiprismatic morphotype of the dinosauroid-prismatic basic type. The pa...
Article
Full-text available
Little is known about the olfactory capabilities of extinct basal (non-neornithine) birds or the evolutionary changes in olfaction that occurred from non-avian theropods through modern birds. Although modern birds are known to have diverse olfactory capabilities, olfaction is generally considered to have declined during avian evolution as visual an...
Article
Approximately 1500 eggshell fragments were recovered from a vertebrate bonebed (NMMNH L-4010) in the late Campanian Fruitland Formation in northwestern New Mexico, a locality that represents one of the few southern occurrences of fossil eggshells in North America. Here, we present the first description of Campanian eggshells from New Mexico and ide...
Article
Full-text available
A well-preserved skull from a previously unknown growth stage for the lambeosaurine hadrosaurid Hypacrosaurus stebingeri from the Campanian of western North America is described. This skull is equivalent in size to the smallest known growth stages for Corythosaurus, Hypacrosaurus altispinus and Lambeosaurus, and allows for a direct comparison of th...
Article
A reappraisal of the eggshell of ratites clarifies aspects of its microstructure and ultrastructure. The phylogenetic usefulness of the eggshell data, consisting of discrete characters, is assessed using eggshell characters alone and by adding the eggshell characters to a data matrix from the literature based on skeletal characters. The resultant t...
Article
Paleosols of the Late Cretaceous Sânpetru Formation (Haţeg Basin, Romania) are the subject of macroscopic, microscopic, and geochemical investigation in order to reconstruct the palaeoenvironmental and palaeoclimatic conditions in which dinosaurs lived. Study of overbank deposits present in an 860-m-thick stratigraphic interval of the Sânpetru Form...
Article
Full-text available
Theropod eggshell is identified for the first time from the Lower Cretaceous of North America. Eggshell microstructure and variability in ornamentation and thickness of this material is comparable to that present in elongatoolithid theropod eggs, known previously only from Asia. This identification is based on re-examination of the holotype of the...
Article
  Egg clutches of non-avian maniraptoran theropods (Dinosauria) are rare, particularly in North America where those of Troodon formosus are the only maniraptoran clutches known. Here we describe a new partial maniraptoran clutch and nesting trace referred to Montanoolithus strongorum oogen. et oosp. nov. (Montanoolithidae oofam. nov.), from the Upp...
Article
Full-text available
This research presents the first quantitative evaluation of the olfactory acuity in extinct theropod dinosaurs. Olfactory ratios (i.e. the ratio of the greatest diameter of the olfactory bulb to the greatest diameter of the cerebral hemisphere) are analysed in order to infer the olfactory acuity and behavioural traits in theropods, as well as to id...
Article
Full-text available
Here we report on the first discovery of shelled eggs inside the body cavity of a fossil turtle and on an isolated egg clutch, both referable to the Cretaceous turtle Adocus. These discoveries provide a unique opportunity to gain insight into the reproductive traits of an extinct turtle and to understand the evolution of such traits among living tu...
Article
A phylogenetic analysis of reproductive and oological (egg) traits of theropod taxa allows determination of the sequence in which these traits evolved in Theropoda. Our results indicate that several avian reproductive traits, such as adults sitting on eggs, asymmetrical eggs, unornamented eggshell surface, and complex eggshell ultrastructure, were...
Article
The “ethmoid complex” is an enigmatic element of the anterior portion of the braincase first described in Tyrannosaurus rex in 1912, which has since been recognized in many non-avian theropods. Because the “ethmoid complex” is a landmark for the reconstruction of the olfactory apparatus of non-avian theropods, we clarify the homology of this struct...
Article
The “ethmoid complex” is an enigmatic element of the anterior portion of the braincase first described in Tyrannosaurus rex in 1912, which has since been recognized in many non-avian theropods. Because the “ethmoid complex” is a landmark for the reconstruction of the olfactory apparatus of non-avian theropods, we clarify the homology of this struct...
Article
A high-resolution study identified a δ13C excursion of -1.8‰ to -2.3‰ in terrestrial organic matter across the Cretaceous-Tertiary (K-T) boundary at two localities in the Scollard Formation of south-central Alberta, one of the northernmost occurrences of the K-T boundary in terrestrial settings. δ13C values are at their lowest within 6 cm above the...
Article
Full-text available
An oviraptosaurian specimen (Dinosauria, Theropoda) from an Upper Cretaceous formation in China retains a pair of shelled eggs in the pelvis, providing direct evidence that oviraptorosaurian dinosaurs laid paired elongatoolithid eggs. The presence of the paired eggs suggests that theropod dinosaurs had two functional oviducts (like crocodiles) but...
Article
Some of the oldest known dinosaur eggs with embryos were reported from Lower Jurassic sediments of South Africa's Elliot Formation. The osteological data from the embryos suggest that the eggs were laid by dinosaurs, and the presence of skeletal materials of the sauropodomorph Massospondylus carinatus at the egg-producing locality prompted the tent...
Article
Description of well-preserved fossil eggshell (oospecies Prismatoolithus levis), recently assigned to the theropod dinosaur Troodon formosus, reveals traits that are shared with the eggshell of both fossil and Recent avians. Bird-like characteristics of troodontid eggshell include: fibres associated with eisospherites that are attached to the bases...
Article
Full-text available
The shell of a turtle, tentatively identified as a eurysternid, was recovered from a Late Jurassic limestone concretion found near the village of Schamhaupten, Germany. Transverse sections through the body cavity revealed four spherical crystalline objects that are embedded in a micritic matrix and surrounded by a thin calcareous crust that superfi...
Article
Full-text available
Eggshell taphonomy often is acknowledged to be worthy of investigation, but few studies have examined factors influencing eggshell preservation. In this study eggshell weathering, fragmentation, dispersal, orientation, and predation were characterized in field and laboratory studies. Modern gull eggshell fragment dispersal and orientation patterns...
Article
A large number of eggshell fragments from a single locality of the lower Eocene (?Wa5-Wa6 biochron) DeBeque Formation of northwestern Colorado are interpreted as representing a single, disintegrated avian egg. These eggshells, and eggshells from two other localities within the formation, are of the ratite morphotype within the ornithoid basic type....
Article
Eggshell fragments collected from the Oldman Formation, southern Alberta, are described as Spheroolithus albertensis, oosp. nov. This oospecies exhibits a spheroolithid microstructure, sagenotuberculate outer surface ornamentation, and a shell thickness of 0.98–1.22 mm. A multilayering pathology of S. albertensis suggests that the egg laying taxon...
Article
Examination of a large number of eggshell fragments collected from the Oldman Formation of southern Alberta reveals a greater ootaxonomic diversity than is known from complete eggs or clutches. Three new oogenera and oospecies of the ornithoid-ratite morphotype and one of the ornithoid-prismatic morphotype are established, based on the eggshell fra...
Article
A clutch of 12 eggs and numerous eggshell fragments recovered from the Oldman Formation at Devil's Coulee, southern Alberta, are described as Prismatoolithus levis oosp.nov. The eggs are elongate with a smooth outer surface and an eggshell structure that is referable to the angustiprismatic morphotype of the dinosauroid-prismatic basic type. The pa...