Julia A Clarke

University of Texas at Austin | UT

Despite making up one of the most ecologically diverse groups of living birds, comprising soaring, diving and giant flightless taxa, the evolutionary relationships and ecological evolution of Anseriformes (waterfowl) remain unresolved. Although Anseriformes have a comparatively rich, global Cretaceous and Paleogene fossil record, morphological data...

A recurrent theme in the geosciences is the persistent need for more student demographic diversity, especially in academic programs. A strategy to make the geosciences inclusive and motivating for one marginalized group may not succeed with another, requiring the search for new approaches. The Geoscience Ambassadors, an extracurricular program for...

Vocal production in birds has been the target of considerable research that mostly has focused on phylogenetically well‐nested songbirds. Anatomical descriptions and recordings of many non‐songbirds have often only focused on a single ontogenetic stage or sex. While basic morphology of the vocal organ (syrinx) of ostrich (Palaeognathae, Struthio ca...

The vocal organ of birds, the syrinx, represents a key innovation in the evolutionary history of vertebrate communication. Three major avian clades: passerines, parrots, and hummingbirds, independently acquired both specialized syringeal structures and vocal-production learning, between which a functional relationship has been proposed but remains...

Natal down is a feather stage that differs in both form and function from the definitive feathers of adult birds. It has a simpler structure that has been speculated to be similar to the body coverings of non-avian dinosaurs. However, inference of the evolution of natal down has been limited by our understanding of its structural variation in extan...

Asteriornis maastrichtensis, from the latest Cretaceous of Belgium, is among the oldest known crown bird fossils, and its three-dimensionally preserved skull provides the most substantial insights into the cranial morphology of early crown birds to date. Phylogenetic analyses recovered Asteriornis as a total-group member of Galloanserae (the clade...

The systematics of Madagascar’s extinct elephant birds remains controversial due to large gaps in the fossil record and poor biomolecular preservation of skeletal specimens. Here, a molecular analysis of 1000-year-old fossil eggshells provides the first description of elephant bird phylogeography and offers insight into the ecology and evolution of...

Previously we showed that authentic peptide sequences could be obtained from 3.8-Ma-old ostrich eggshell (OES) from the site of Laetoli, Tanzania (Demarchi et al., 2016). Here we show that the same sequences survive in a > 6.5 Ma OES recovered from a palaeosteppe setting in northwestern China. The eggshell is thicker than those observed in extant s...

High disparity among avian forelimb and hind limb segments in crown birds relative to non-avialan theropod dinosaurs, potentially driven by the origin of separate forelimb and hind limb locomotor modules, has been linked to the evolution of diverse avian locomotor behaviors. However, this hypothesized relationship has rarely been quantitatively inv...

The end Cretaceous mass extinction was marked by a dramatic change in biodiversity, and the extinction of all non-avian dinosaurs. To understand the diversity of dinosaur clades prior to this event, as well as recovery by avian dinosaurs (birds), we need a better understanding of the global fossil record. However, the fossil record from southern lo...

Currently known structural colors in feathers are caused by light scattering from periodic or amorphous arrangements of keratin, melanin, and air within barbs and barbules that comprise the feather vane. Structural coloration in the largest part of the feather, the central rachis, is rare. Here, we report on an investigation of the physical mechani...

Despite making up one of the most ecologically diverse groups of living birds, comprising soaring, diving and giant flightless taxa, the evolutionary relationships and ecological evolution of Anseriformes (waterfowl) remain unresolved. Although Anseriformes have a comparatively rich, global Cretaceous and Paleogene fossil record, morphological data...

The eggshell of reptiles ensures water and gas exchange during incubation, and plays a key role in their reproductive success. Many clade-specific adaptations of eggshell microstructure have been associated with incubation and life history strategies in extant (birds, crocodilians, turtles, and lepidosaurs) and extinct taxa (e.g. non-avian dinosaur...

Reptile eggshell ensures water and gas exchange during incubation and plays a key role in reproductive success. The diversity of reptilian incubation and life history strategies has led to many clade-specific structural adaptations of their eggshell, which have been studied in extant taxa (i.e. birds, crocodilians, turtles, and lepidosaurs). Most s...

The oldest authenticated peptide sequences to date were reported in 2016 from 3.8 Ma old ostrich eggshell (OES) from the site of Laetoli, Tanzania (Demarchi et al., 2016). Here we demonstrate survival of the same sequences in 6.5-9 Ma OES recovered from a palaeosteppe setting in northwestern China. The eggshell is thicker than those observed in ext...

A second K/Pg boundary interval in the northern sector of the Antarctic Peninsula on Vega Island has been proposed, yet current temporal resolution of these strata prohibits direct testing of this hypothesis. To not only test for the existence of a K/Pg boundary on Vega Island but also provide increased age resolution for the associated vertebrate...

Significance The controversy over the taxonomic identity of the eggs exploited by Australia’s first people around 50,000 y ago is resolved. The birds that laid these eggs are extinct, and distinguishing between two main candidates, a giant flightless “mihirung” Genyornis and a large megapode Progura , had proven impossible using morphological and g...

Although an increasing number of studies are combining skeletal and neural morphology data in a phylogenetic context, most studies do not include extinct taxa due to the rarity of preserved endocasts. The early Eocene avifauna of the Fur Formation of Denmark presents an excellent opportunity for further study of extinct osteological and endocranial...

The globally distributed extinct clade Enantiornithes comprises the most diverse early radiation of birds in the Mesozoic with species exhibiting a wide range of body sizes, morphologies, and ecologies. The fossil of a new enantiornithine bird, Brevirostruavis macrohyoideus gen. et sp. nov., from the Lower Cretaceous Jiufotang Formation in Liaoning...

Of the more than 6,000 members of the most speciose avian clade, Passeriformes (perching birds), only the five species of dippers (Cinclidae, Cinclus) use their wings to swim underwater. Among nonpasserine wing‐propelled divers (alcids, diving petrels, penguins, and plotopterids), convergent evolution of morphological characteristics related to thi...

Carotenoids are pigments responsible for most bright yellow, red, and orange hues in birds. Their distribution has been investigated in avian plumage, but the evolution of their expression in skin and other integumentary structures has not been approached in detail. Here, we investigate the expression of carotenoid‐consistent coloration across tiss...

Birds today are the most diverse clade of terrestrial vertebrates, and understanding why extant birds (Aves) alone among dinosaurs survived the Cretaceous-Paleogene mass extinction is crucial to reconstructing the history of life. Hypotheses proposed to explain this pattern demand identification of traits unique to Aves. However, this identificatio...

While the state of the art has been described for recording bird songs and calls, there are no described best practices for collecting and preserving the avian vocal organ, the syrinx. In addition to skins and skeletal preparations, field collection of tissues for DNA sequencing has become a common practice. Protocols for such tissue collection oft...

Birds share an array of unique characteristics among extant land vertebrates. Among these, external and microstructural characteristics of extant bird eggs have been linked to changes in reproductive strategy that arose among non‐avian theropod dinosaurs. More recently, differences in egg proportions recovered in crown birds relative to other dinos...

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Carotenoids are among the most ubiquitous pigments that produce bright colors in animals, and create most of the vibrant yellows, oranges, and reds in living birds. While they are comparatively well characterized in the plumage of many species, these pigments are also common in avian bare parts (e.g. skin, beak) but their phylogenetic distribution...

A recent study by Norell et al. (2020) described new egg specimens for two dinosaur species, identified as the first soft-shelled dinosaur eggs. The authors used phylogenetic comparative methods to reconstruct eggshell type in a sample of reptiles, and identified the eggs of dinosaurs and archosaurs as ancestrally soft-shelled, with three independe...

The stem lineage relationships and early phenotypic evolution of Charadriiformes (shorebirds) and Gruiformes (rails, cranes, and allies) remain unresolved. It is still debated whether these clades are sister-taxa. New phylogenetic analyses incorporating Paleogene fossils have the potential to reveal the evolutionary connections of these two specios...

Egg size and structure reflect important constraints on the reproductive and life-history characteristics of vertebrates. More than two-thirds of all extant amniotes lay eggs. During the Mesozoic era (around 250 million to 65 million years ago), body sizes reached extremes; nevertheless, the largest known egg belongs to the only recently extinct el...

Synthesizing data from three years of mixed methods classroom design research, this study reports on a model for a disciplinarily diverse course-based research experience (CBRE) to enhance university-based science learning. By emphasizing disciplinary mixing, mentorship and peer feedback, the experience develops scientific skills, identities and di...

One of the two lineages of extant birds resulting from its deepest split, Palaeognathae, has been reported not to exhibit structural coloration in feathers, affecting inferences of ancestral coloration mechanisms in extant birds. Structural coloration in facial skin and eggshells has been shown in this lineage, but has not been reported in feathers...

Relative brain sizes in birds can rival those of primates, but large-scale patterns and drivers of avian brain evolution remain elusive. Here, we explore the evolution of the fundamental brain-body scaling relationship across the origin and evolution of birds. Using a comprehensive dataset sampling> 2,000 modern birds, fossil birds, and theropod di...

Natural history collections (NHCs) are the foundation of historical baselines for assessing anthropogenic impacts on biodiversity. Along these lines, the online mobilization of specimens via digitization—the conversion of specimen data into accessible digital content—has greatly expanded the use of NHC collections across a diversity of disciplines....

Natural history museums are unique spaces for interdisciplinary research and educational innovation. Through extensive exhibits and public programming and by hosting rich communities of amateurs, students, and researchers at all stages of their careers, they can provide a place-based window to focus on integration of science and discovery, as well...

The middle-late Eocene of Antarctica was characterized by dramatic change as the continent became isolated from the other southern landmasses and the Antarctic Circumpolar Current formed. These events were crucial to the formation of the permanent Antarctic ice cap, affecting both regional and global climate change. Our best insight into how life i...

The Magallanes-Austral foreland basin preserves an important record of orogenesis and landscape evolution in the Patagonian Andes of Chile and Argentina. Throughout the retroarc foreland basin, a regional disconformity with little to no angular discordance separates Upper Cretaceous–lower Paleocene strata from overlying deposits of diachronous Eoce...

Numerous skeletal remains recovered in situ from the late early to middle Paleocene Takatika Grit of Chatham Island, New Zealand, are among the oldest known fossils attributed to the penguin clade (Aves, Sphenisciformes). They represent a new medium-sized taxon, for which we erect a new genus and species, and a second, notably larger form. These ne...

There has been much discussion over whether basal birds (e.g. Archaeopteryx and Confuciusornis) exhibited active flight. A recent study of barb angles has suggested they likely could not but instead may have exhibited a gliding phase. Pennaceous primary flight feathers were proposed to show significant shifts in barb angle values of relevance to th...

Background The lake deposits of the informal Ruby Paper Shale unit, part of the Renova Formation of Montana, have yielded abundant plant fossils that document Late Eocene – Early Oligocene global cooling in western North America. A nearly complete small bird with feather impressions was recovered from this unit in in 1959, but has only been informa...

Despite having one of the most robust fossil records within core-gruiform birds (rails, cranes, and allies), the biogeographic history of Gruidae (cranes) and key drivers of diversification within this group remain largely unknown. The Eogruidae of Eurasia represent some of the earliest known crane-like fossils. Here, we present description of a ne...

Cape Marsh, located on the eastern end of Robertson Island to the east of the Antarctic Peninsula, exposes an isolated outcrop of Late Cretaceous sedimentary strata. The outcrop is approximately 120 km southwest of the much better-studied exposures of similar age on and around James Ross Island (JRI); as such, its remoteness has complicated both lo...

Numerous isolated and associated skeletal remains recovered in situ from the late early to middle Paleocene Takatika Grit of Chatham Island, New Zealand, represent some of the oldest known penguin fossils (Aves: Sphenisciformes). Among these remains we recognise a new medium-sized taxon, and another notably larger form. The new penguins, as well as...

The Magallanes-Austral foreland basin records orogenesis and landscape evolution in the Patagonian Andes of Chile and Argentina. Throughout the retroarc foreland basin, a regional disconformity separates Upper Cretaceous-lower Paleocene strata from overlying diachronous Eocene-Miocene deposits. We present new data from a fossiliferous mixed marine/...

Although the fossil record of non-avian dinosaurs from the Cretaceous of Antarctica is the poorest of any continent, fossils representing at least five major taxonomic groups (Ankylosauria, early-diverging Ornithopoda, Hadrosauridae, Titanosauria, and Theropoda) have been recovered. All come from Upper Cretaceous (Coniacian–Maastrichtian) marine an...

The fossil record of birds from Antarctica is concentrated in the James Ross Basin, located in northeast of the Antarctic Peninsula. Birds are here represented by an extensive Paleogene record of penguins (Sphenisciformes) and Cretaceous-Paleogene record of Anseriformes, followed by other groups with a minor representation (Procellariiformes, Falco...

Understanding of the Asian early Paleogene avifauna is limited relative to that of North American and European avifauna of the same period. While major patterns of mammalian faunal exchange among these three regions across the Paleocene/Eocene boundary have been described, much less is known about the dynamics of bird diversity over the same time i...

Osmoregulation in birds is complicated, with different organs acting concurrently to regulate this physiological process. Of particular interest is how the urinary excretions of birds can remove excess nitrogen while minimizing the need for dietary water and balancing the physiological demands of oviparity. It has long been concluded from chemical...

The ability to fly has been lost in many groups of birds. A comparison of the wing structures and genomes of flighted and non-flighted species of steamer duck highlights a possible mechanism for the loss of flight. Genomes of flighted and flightless steamer ducks compared. Falkland Flightless Steamerduck 'steaming' on water

Lithornithids are volant stem palaeognaths from the Paleocene‐Eocene. Except for these taxa and the extant neotropical tinamous, all other known extinct and extant palaeognaths are flightless. Investigation of properties of the lithornithid wing and its implications for inference of flight style informs understood locomotor diversity within Palaeog...

Natural history collections (NHCs) are the foundation of historical baselines for assessing anthropogenic impacts on biodiversity. Along these lines, the online mobilization of specimens via digitization–the conversion of specimen data into accessible digital content–has greatly expanded the use of NHC collections across a diversity of disciplines....

Natural history collections (NHCs) are the foundation of historical baselines for assessing anthropogenic impacts on biodiversity. Along these lines, the online mobilization of specimens via digitization–the conversion of specimen data into accessible digital content–has greatly expanded the use of NHC collections across a diversity of disciplines....

The giant carnivorous phorusrhacid bird Phorusrhacos longissimus (Aves, Cariamiformes) was first described in 1887 by Florentino Ameghino on the basis of a jaw fragment. The majority of a skull of the species still encased in crumbling rock was preserved only long enough for illustrations to be made by Carlos Ameghino in the field and for a brief d...

In 2006, a partial avian femur (South Dakota School of Mines and Technology (SDSM) 78247) from the Upper Cretaceous (Maastrichtian) Sandwich Bluff Member of the López de Bertodano Formation of Sandwich Bluff on Vega Island of the northern Antarctic Peninsula was briefly reported as that of a cariamiform-a clade that includes extant and volant South...

Evolutionary convergence has been long considered primary evidence of adaptation driven by natural selection and provides opportunities to explore evolutionary repeatability and predictability. In recent years, there has been increased interest in exploring the genetic mechanisms underlying convergent evolution, in part, owing to the advent of geno...

Evolutionary convergence has been long considered primary evidence of adaptation driven by natural selection and provides opportunities to explore evolutionary repeatability and predictability. In recent years, there has been increased interest in exploring the genetic mechanisms underlying convergent evolution, in part, owing to the advent of geno...

Palaeognathae is an extant clade of birds with body masses ranging over several orders of magnitude of kilograms, including the largest-yet described terrestrial avian species. Most studies have suggested flight loss and increasing body size began early in its evolutionary history, prior to the divergence of the major extant lineages. However, rece...

Phenotypic data are crucial for understanding genotype–phenotype relationships, assessing the tree of life and revealing trends in trait diversity over time. Large‐scale description of whole organisms for quantitative analyses (phenomics) presents several challenges, and technological advances in the collection of genomic data outpace those for phe...

Natural history museums are unique spaces for interdisciplinary research and for educational innovation. Through extensive exhibits and public programming and by hosting rich communities of amateurs, students, and researchers at all stages of their careers, they provide a place-based window to focus on integration of science and discovery, as well...

Natural history museums are unique spaces for interdisciplinary research and for educational innovation. Through extensive exhibits and public programming and by hosting rich communities of amateurs, students, and researchers at all stages of their careers, they provide a place-based window to focus on integration of science and discovery, as well...

All roads lead to regulation Species from widely divergent taxa can experience similar changes in traits. What underlying genetic drivers cause these parallel changes remains an open question. Sackton et al. looked across groups of birds that have repeatedly lost flight, the ratites and tinamous, and found that there is convergence in the regulator...

Metabolism links organisms to their environment through its effects on thermoregulation, feeding behaviour and energetics. Genes involved in metabolic processes have known pleiotropic effects on some melanic colour traits. Understanding links between physiology and melanic colour is critical for understanding the role of, and potential constraints...

Integumentary patterns and colors can differentiate species, sexes, and life changes and can inform on habitat and ecology. However, they are rarely preserved in the fossil record. Here, we report on an extremely well-preserved specimen of the Cretaceous bird Confuciusornis with unprecedented complexity, including small spots on the wings, crest, a...

Iodine staining combined with X-ray computed tomography (CT) has become a core approach in anatomy, offering three-dimensional and essentially non-destructive imaging of soft tissues. Although there have been rapid advances in methodologies and techniques, the mechanisms underlying diffusible iodine contrast-enhanced CT are not yet fully understood...

The recently extinct Malagasy elephant birds (Palaeognathae, Aepyornithiformes) included the largest birds that ever lived. Elephant bird neuroanatomy is understudied but can shed light on the lifestyle of these enigmatic birds. Palaeoneurological studies can provide clues to the ecologies and behaviours of extinct birds because avian brain shape i...

In its most basic conception, a novelty is simply something new. However, when many previously proposed evolutionary novelties have been illuminated by genetic, developmental, and fossil data, they have refined and narrowed our concept of biological "newness." For example, they show that these novelties can occur at one or multiple levels of biolog...

Penguins exhibit an array of derived feather features and color-producing mechanisms, including distinct melanosome morphologies and beta-keratin nanofibers that produce blue structural color. Several morphologies have been proposed to have hydrodynamic or insulatory functions. An understanding of the distribution of these morphologies over the bod...

Zygodactylidae are an extinct lineage of perching birds characterized by distinct morphologies of the foot and wing elements. Although the clade has a complex taxonomic history, current hypotheses place Zygodactylidae as the sister taxon to Passeriformes (i.e., songbirds). Given the rather sparse fossil record of early passeriforms, the description...