Ryan C McKellar

Royal Saskatchewan Museum · Palaeontology

One new extinct genus and six new extinct species of Zopheridae are described and illustrated from Eocene Baltic amber: Usechus andrushchenkoi Alekseev et Bukejs sp. nov., Coxelus carstengroehni Alekseev et Bukejs sp. nov., Paha vanivanitatum Alekseev et Bukejs sp. nov., Lasconotus tenebrisilvarum Alekseev et Bukejs sp. nov., Helioctamenus groehni...

All 14,000 extant ant species descended from the same common ancestor, which lived 140–120 million years ago (Ma). While modern ants began to diversify in the Cretaceous, recent fossil evidence has demonstrated that older lineages concomitantly occupied the same ancient ecosystems. These early-diverging ant lineages, or stem ants, left no modern de...

Based on a well-preserved specimen in Eocene Baltic amber, a new species Globicornis samlandensis sp. nov. (Coleoptera: Dermestidae) is described and illustrated. The new fossil species differs from extinct congeners in having antennomere 10 short and subtriangular with a rounded apex, and about as long as wide; while the pronotum and elytra are un...

Amber is a material prized in the manufacture of jewellery and in paleobiological studies, and Cretaceous Burmese amber is particularly valued for its exceptional richness in fossil organisms. Because of its transparency, amber generally provides researchers with clear views of exceptionally preserved fossils. If amber is polished, it provides mult...

Based on a single specimen from Eocene Baltic amber, Donacia (Protodonacia) bienkowskii subgen. et sp. nov. is described and illustrated. The new species is studied and illustrated in detail using X-ray microcomputed tomography (μCT). It is the first described species of Donaciinae (Coleoptera: Chrysomelidae) from Baltic amber and from fossil resin...

This study details the quality of preservation of amber deposits in the Eocene. Through Baltic amber crack-out studies using Synchrotron Micro-Computed Tomography and Scanning Electron Microscopy it was found that the cuticle of a specimen of leaf beetle (Crepidodera tertiotertiaria (Alticini: Galerucinae: Chrysomelidae)) is exceptionally well pres...

This study details the quality of organic preservation of amber deposits in the Eocene. Through Baltic amber crack-out studies using Synchrotron Micro-Computed Tomography and Scanning Electron Microscopy it was found that the cuticle of a specimen of leaf beetle (Crepidodera tertiotertiaria) (Alticini: Galerucinae: Chrysomelidae)) is exceptionally...

Abstract: The Late Cretaceous mosasaur Prognathodon has a global distribution, with specimens found in Campanian and Maastrichtian marine deposits in Europe, New Zealand, North America, and the Middle East. Canadian Prognathodon material had hitherto been reported only from Alberta. Herein is described the first partial skull and post-crania of Pro...

Previously, only a single member of Pan‐Kinosternidae (Yelmochelys rosarioae) had been documented from the Late Cretaceous epoch. In this report we describe a new pan‐kinosternid genus and species, herein named Leiochelys tokaryki, based on a nearly complete, articulated skeleton from the Late Cretaceous (Maastrichtian) Frenchman Formation of Saska...

Two specimens of Borealosuchus collected from the lower facies of the Ravenscrag Formation (earliest Paleocene) in southern Saskatchewan are described. One largely complete individual featuring a partial skull, mandible, and postcrania can be unambiguously assigned to Borealosuchus griffithi Wu et al. 2001a. The other specimen consisting of skull a...

Among non-avian dinosaurs, fossilized skin is most comprehensively represented in the hadrosaurids. Here we provide the first full descriptions of hadrosaurid skin from the Late Cretaceous (Maastrichtian) Frenchman Formation in southern Saskatchewan. Based on the geological age and associated skeletal material, the specimen is tentatively identifie...

Borealosuchus is among the best known early crocodyliform genera from the latest Cretaceous/early Cenozoic terrestrial fossil assemblages of continental North America. The record of Borealosuchus in the Canadian Provinces is nearly nonexistent compared with coeval units in North Dakota, South Dakota, Montana, and Wyoming. In this study we present t...

Amber fossils provide snapshots of the anatomy, biology, and ecology of extinct organisms that are otherwise inaccessible. The best-known fossils in amber are terrestrial arthropods—principally insects—whereas aquatic organisms are rarely represented. Here we present the first record of true crabs (Brachyura) in amber—from the Cretaceous of Myanmar...

Two new genera, Burserphites and Mesoserphites, belonging to the subfamily Serphitinae (Serphitidae, Hymenoptera) are described from Burmese mid-Cretaceous amber. Two new species are erected within Buserphites n. gen.: B. applanatus, and B. myanmarensis, and five new species are established within Mesoserphites n. gen.: M. annulus, M. giganteus, M....

Based on material originating from five amber collections of Eocene Baltic amber, Protostomopsis pandema gen. et sp. nov. is described and illustrated using X-ray micro-computed tomography. It is the first formally described extinct species of Cerylonidae, and the first known Palaearctic representative of the subfamily Ostomopsinae. As such, the ne...

The Frenchman Formation (Maastrichtian) exposed within Chambery Coulee in southwestern Saskatchewan, Canada, has yielded exceptional vertebrate fauna specimens, including one of the largest known Tyrannosaurus rex individuals. The site has excellent preservation of a rich and diverse paleobotanical assemblage containing amber, which is analyzed in...

The description of an extinct species of Metaclisa Jacquelin du Val, 1861 (Tenebrionidae) is presented. This genus and the tribe Metaclisini are recorded as fossils for the first time, from Eocene Baltic amber. The new species Metaclisa ottoi sp. nov. belongs to the subgenus Trichometaclisa subgen. nov. and differs from all other Metaclisini in pos...

Chelonariidae, or turtle beetles, are rarely represented in the fossil record. Two new extinct species of this thermophilous coleopteran family, Chelonarium andabata Alekseev and Bukejs sp. nov. and Ch. dingansich Alekseev and Bukejs sp. nov., are described and illustrated from Eocene Baltic amber using X-ray micro-computed tomography (micro-CT). T...

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

The Society of Vertebrate Paleontology (SVP) has recently circulated a letter, dated 21st April, 2020, to more than 300 palaeontological journals, signed by the President, Vice President and a former President of the society (Rayfield et al. 2020). In this letter, significant changes to the common practices in palaeontology are requested. In our pr...

Recently, the Society of Vertebrate Paleontology (SVP) has sent around a letter, dated 21st April, 2020 to more than 300 palaeontological journals, signed by the President, Vice President and a former President of the society (Rayfield et al. 2020). The signatories of this letter request significant changes to the common practices in palaeontology....

Recent discoveries of enantiornithine birds trapped in amber have decreased the lower size limit of members of this clade, increased their morphological diversity, and provided significant new data regarding their plumage. Here, we describe a new specimen that consists of the distal extremities of both forelimbs and hindlimbs. Size and morphology s...

We welcome any new interpretation or alternative hypothesis regarding the taxonomic affinity of the enigmatic Oculudentavis khaungraae. However, here we demonstrate that Li et al. have failed to provide conclusive evidence for the reidentification of HPG-15-3 as a squamate. We analyse this specimen in a matrix that includes a broad sample of diapsi...

A male representative of the extinct species Calomicrus eocenicus Bukejs et Bezděk, 2014 (Chrysomelidae: Galerucinae) is found and described for the first time from Eocene Baltic amber using X-ray microtomography. The aedeagus is well preserved within the body cavity of the specimen, and it is illustrated in detail. This fossil species exhibits dis...

Amber deposits and dinosaur bonebeds provide some of the most detailed sources of information on terrestrial ecosystems, but these sources have rarely been studied in tandem. The Pipestone Creek bonebed from the Campanian Wapiti Formation of Alberta, Canada, provides an opportunity to explore both data sources in the same deposit for the first time...

Recent discoveries of enantiornithine remains in Burmese amber have provided a wealth of paleobiological data on this extinct clade of Mesozoic birds. Amber, as a unique medium of fossilization, preserves in three dimensions structures with details unmatched elsewhere in the fossil record. This provides the opportunity to combine osteological infor...

Skeletal inclusions in approximately 99-million-year-old amber from northern Myanmar provide unprecedented insights into the soft tissue and skeletal anatomy of minute fauna, which are not typically preserved in other depositional environments1–3. Among a diversity of vertebrates, seven specimens that preserve the skeletal remains of enantiornithin...

All of the bird specimens previously recovered from Burmese amber have belonged to either immature specimens, or small-bodied taxa belonging to Enantiornithes. This has led to questions about whether the size bias inherent to preservation in amber has limited inclusions to smaller individuals or species, or if the avifauna of the amber-producing fo...

Even in the absence of associated skeletal material, isolated feathers in amber remain of high scientific interest. The remarkable preservation of these delicate structures in amber implies a potential for significantly improving our knowledge of feather evolution and diversity. A large sample set of 150 Burmese amber specimens (Upper Cretaceous, ~...

A new fossil species of the silvanid flat bark beetle, Airaphilus simulacrum Alekseev, Bukejs et McKellar sp. nov. (Coleoptera: Silvanidae) is illustrated and described based on two specimens from Eocene Baltic amber. A second specimen of the confamilial fossil taxon Mistran ot Alekseev et Bukejs, 2016 is reported and imaged using synchrotron X-ray...

Hadrosaurian dinosaurs were abundant in the Late Cretaceous of North America, but their habitats remain poorly understood. Cretaceous amber is also relatively abundant, yet it is seldom found in direct stratigraphic association with dinosaur remains. Here we describe an unusually large amber specimen attached to a Prosaurolophus jaw, which reveals...

A new fossil species of the silvanid flat bark beetle genus Cathartosilvanus Grouvelle is described and illustrated from Baltic amber. Cathartosilvanus siteiterralevis sp. nov. differs from recent and fossil congeners in the distinct, sharp denticle found along its posterior pronotal angle. The phenomenon of specific body parts becoming disconnecte...

Since the first skeletal remains of avians preserved in amber were described in 2016, new avian remains trapped in Cretaceous-age Burmese amber continue to be uncovered, revealing a diversity of skeletal and feather morphologies observed nowhere else in the Mesozoic fossil record. Here we describe a foot with digital proportions unlike any previous...

The eggs of fish, amphibians, and many invertebrates are soft, delicate structures that are only rarely preserved in the fossil record. Here we report egg masses preserved as inclusions in mid-Cretaceous amber deposits of Myanmar. Of five specimens recovered, three of the egg masses probably pertain to insects, but the other two appear different. O...

Three new species of Cyphaspides are proposed: C. ammari, C. nicoleae , and C. pankowskiorum . These species are based on specimens obtained from Middle Devonian (Eifelian) strata of the Bou Tchrafine Group, near Erfoud, in the Province of Errachidia, southeastern Morocco. The present contribution enhances our knowledge of Cyphaspides by providing...

Recent discoveries of vertebrate remains trapped in middle Cretaceous amber from northern Myanmar [1, 2] have provided insights into the morphology of soft-tissue structures in extinct animals [3-7], in particular, into the evolution and paleobiology of early birds [4, 8, 9]. So far, five bird specimens have been described from Burmese amber: two i...

Cacomorphocerus eocenicus sp. nov. (Coleoptera: Cantharidae) is described and illustrated on the base of one well-preserved specimen from Eocene Baltic amber. It is the sixth described species of this fossil genus, and it is characterized by possessing antennomeres 6–7 that are slightly modified and dilated (while antennomeres 3–9 are modified, and...

Over the last three years, Burmese amber (~99 Ma, from Myanmar) has provided a series of immature enantiornithine skeletal remains preserved in varying developmental stages and degrees of completeness. These specimens have improved our knowledge based on compression fossils in Cretaceous sedimentary rocks, adding details of three-dimensional struct...

Zootaxa 4550 (4): 565-572 https://www.mapress.com/j/zt/ Article 565 https://doi.org/10.11646/zootaxa.4550.4.6 http://zoobank.org/urn:lsid:zoobank. Abstract Based on a well-preserved specimen from Eocene Baltic amber, the second fossil species belonging to the genus Pycno-merus Erichson (Coleoptera: Zopheridae: Zopherinae), P. agtsteinicus Bukejs, A...

Over the last 20 years, compression fossils of feathers surrounding dinosaurs have greatly expanded our understanding of the origin and evolution of feathers. One of the most peculiar feather morphotypes discovered to date are rachis dominated feathers (RDFs), which have also been referred to as proximally ribbon-like pennaceous feathers (PRPFs). T...

Gastropods are generally rare in amber. In this paper we describe an example of exceptional soft-bodied preservation in a fossil terrestrial mollusk-a snail shell with some tissue, including part of the cephalic region (head) with a tentacle and inferred eye stalk, and potentially part of the foot and operculum. The snail, a probable juvenile, is p...

Deuterium exchange experiments on modern and fossil plant resins (amber) were conducted to assess to what extent diagenetic alteration can overprint the stable hydrogen (δ²H) and carbon (δ¹³C) isotopic composition of these materials. Pairs of resins and amber fragments were placed together with deuterated water in sealed quartz-glass tubes to assur...

We present the first known fossilized snake embryo/neonate preserved in early Late Cretaceous (Early Cenomanian) amber from Myanmar, which at the time, was an island arc including terranes from Austral Gondwana. This unique and very tiny snake fossil is an articulated postcranial skeleton, which includes posterior precloacal, cloacal, and caudal ve...

Synchrotron-based techniques offer a wealth of elemental, molecular, and structural insights in biological samples, but the application of these techniques to fossils is a relatively new development. Here we examine how synchrotron radiation micro X-ray fluorescence (SR µXRF) may be used to investigate the chemical composition of insects trapped in...

Ambers—fossilized plant resins—are a rich and unique source of paleoecological data due to their ability to preserve soft body fossils. However, interpretations concerning their environmental context are often hampered by uncertainties in the relationship between assemblages of inclusions and geological context, particularly in the case of secondar...

Cretaceous amber from Myanmar (∼99 Ma Burmese amber) has become a valuable supplement to the traditional skeletal record of small theropod dinosaurs preserved in sedimentary rocks, particularly for coelurosaurs and enantiornithines. The specimens recovered from this deposit preserve skeletal material and soft tissues in unmatched detail. This provi...

A new genus and species from the subfamily Pemphredoninae (Hymenoptera: Crabronidae) is described from the Upper Cretaceous amber of Myanmar, commonly known as Burmese amber. A complete, illustrated description is provided. Colmepsiterona cumcarena n. gen. et sp. represents the third record of the subfamily in the deposit, as well as the tenth of t...

The mid-Cretaceous Burmese amber (~99 Ma, Myanmar), widely known for exquisite preservation of theropods, also yields microfossils, which can provide important contextual information on paleoenvironment and amber formation. We report the first Cretaceous ostracod in amber-the gigantic (12.9 mm) right valve of an exclusively marine group (Myodocopa:...

Hemicoelus favonii sp. nov. is described and illustrated from Eocene Baltic amber. This new fossil species differs from extant congeners in having 11-segmented antennae; a metathoracic ventrite with large impression in its anterior portion; a pronotum distinctly narrower than the elytral base region; the posterior suture of abdominal ventrite 1 wea...

Burmese amber has recently provided some detailed glimpses of plumage, soft tissues, and osteology of juvenile enantiornithine birds, but these insights have been restricted to isolated wing apices. Here we describe nearly half of a hatchling individual, based on osteological and soft tissue data obtained from the skull, neck, feet, and wing, and i...

In his correspondence, Markus Lambertz [1] raises some concerns about the phylogenetic placement and feather development of DIP-V-15103, the amber-entombed tail section that we recently reported [2] as fragmentary remains of a non-pygostylian coelurosaur (likely within the basal part of Coelurosauria). We here would like to respond to these concern...

In the two decades since the discovery of feathered dinosaurs [1-3], the range of plumage known from non-avialan theropods has expanded significantly, confirming several features predicted by developmentally informed models of feather evolution [4-10]. However, three-dimensional feather morphology and evolutionary patterns remain difficult to inter...

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009;...

This plot is not part of the published stance but derives from it. The plot shows the number of authors by geographic region (courtesy of Dr. Diego Astua).

Synchrotron-based techniques offer a wealth of elemental, molecular, and structural insights in biological samples, but the application of these techniques to fossils is a relatively new development. Here we examine how Synchrotron Radiation Micro X-Ray Fluorescence (SR µXRF) provides insights into the chemical composition of insects trapped in amb...

Synchrotron-based techniques offer a wealth of elemental, molecular, and structural insights in biological samples, but the application of these techniques to fossils is a relatively new development. Here we examine how Synchrotron Radiation Micro X-Ray Fluorescence (SR µXRF) provides insights into the chemical composition of insects trapped in amb...

Based on two relatively well-preserved specimens from Eocene Baltic amber, Passandra septentrionaria sp. nov. is described and illustrated. It is the first formally described species of Passandridae from Baltic amber, and the first known European representative of the family. The global distribution of extant Passandra Dalman is mapped, and the his...

Two new genera and species belonging to the family Scolebythidae are described from mid-Cretaceous amber of Myanmar, Cursoribythus silvestris and Siccibythus musculosus. These taxa are introduced into the current phylogenetic tree of the family, in order to analyze their relationships and observe their impacts on our understanding of the family. Th...

Our knowledge of Cretaceous plumage is limited by the fossil record itself: compression fossils surrounding skeletons lack the finest morphological details and seldom preserve visible traces of colour, while discoveries in amber have been disassociated from their source animals. Here we report the osteology, plumage and pterylosis of two exceptiona...

Supplementary Figures 1-15, Supplementary Table 1, Supplementary Discussion and Supplementary References