Marine ecosystems have entered the Anthropocene

Sampling of foraminifera found in a sediment core from the Caribbean, dating back to before the Industrial Revolution. CREDIT MICHAL KUCERA

Anthropogenic climate change and ocean acidification resulting from the emission of vast quantities of CO2 and other greenhouse gases pose a considerable threat to ecosystems and modern society. Planktonic foraminifera are a group of marine zooplankton that made their first appearance in the Late Triassic. Although, identifying the first occurrence of planktonic foraminifera is complex, with many suggested planktonic forms later being reinterpreted as benthic. They are present in different types of marine sediments, such as carbonates or limestones, and are excellent biostratigraphic markers. Their test are made of  globular chambers composed of secrete calcite or aragonite, with no internal structures and different patterns of chamber disposition: trochospiral, involute trochospiral and planispiral growth. During the Cenozoic, some forms exhibited supplementary apertures or areal apertures. The tests also show perforations and a variety of surface ornamentations like cones, short ridges or spines. The phylogenetic evolution of planktonic foraminifera are closely associated with global and regional changes in climate and oceanography.

John Murray, naturalist of the CHALLENGER Expedition (1872-1876) found that differences in species composition of planktonic foraminifera from ocean sediments contain clues about the temperatures in which they lived. The ratio of heavy and light Oxygen in foraminifera shells can reveal how cold the ocean was and how much ice existed at the time the shell formed. Another tool to reconstruct paleotemperatures is the ratio of magnesium to calcium (Mg/Ca) in foraminiferal shells. Mg2+ incorporation into foraminiferal calcite  is influenced by the temperature of the surrounding seawater, and the Mg/Ca ratios increase with increasing temperature.

Planktonic foraminifera from the Sargasso Sea in the North Atlantic Ocean. (Photograph courtesy Colomban de Vargas, EPPO/SBRoscoff.)

Analyzing previously collected sediment samples from over 3,500 sites around the world’s ocean, researchers found that the composition of the planktonic foraminifera has changed significantly since the pre-industrial period. The shifts in planktonic foraminifera are indicative of a more-general phenomenon across marine ecosystem, with zooplankton communities shifting poleward by an average 374 miles as a result of warming ocean temperatures.

Human activity is a major driver of the dynamics of Earth system. After the World War II, the impact of human activity on the global environment dramatically increased. Ocean warming reduces the solubility of oxygen, and raises metabolic rates accelerating the thermal stratification.

References:

Jonkers, L., Hillebrand, H., & Kucera, M. (2019). Global change drives modern plankton communities away from the pre-industrial state. Nature. doi:10.1038/s41586-019-1230-3

Advertisements

Introducing Moros intrepidus, the harbinger of doom.

Moros intrepidus. Credit: Jorge Gonzalez

Tyrannosauroidea, the superfamily of carnivorous dinosaurs that includes the iconic Tyrannosaurus rex, originated in the Middle Jurassic, approximately 165 million years ago, and was a dominant component of the dinosaur faunas of the Northern Hemisphere. All tyrannosaurs were bipedal predators characterized by premaxillary teeth with a D-shaped cross section, fused nasals, extreme pneumaticity in the skull roof and lower jaws, a pronounced muscle attachment ridge on the ilium, and an elevated femoral head. But for most of their evolutionary history, tyrannosauroids were mostly small-bodied animals and only reached gigantic size during the final 20 million years of the Cretaceous. Now, the discovery of a new, diminutive tyrannosauroid, Moros intrepidus gen. et sp. nov., shed lights on the successful radiation of Campanian tyrannosauroids.

The holotype (NCSM 33392), preserves a partial right hind limb including portions of the femur, tibia, second and fourth metatarsals, and phalanges of the fourth pedal digit. It was recovered from the lower Mussentuchit Member (6–7 m above the Ruby Ranch contact), upper Cedar Mountain Formation, Emery County, Utah, USA. This small-bodied, gracile-limbed tyrannosauroid lived about 96 million years ago. The name derived from Greek word Moros (an embodiment of impending doom) in reference to the establishment of the Cretaceous tyrannosauroid lineage in NA, and the Latin word intrepidus (intrepid), in reference to the hypothesized intracontinental dispersal of tyrannosaurs during this interval.

Bone microstructure of M. intrepidus (NCSM 33392). From Zanno et al., 2019.

NCSM 33392 derives from a skeletally immature individual (6-7 years) nearing adult size . According to the histological analysis, M. intrepidus exhibits a moderate growth rate, similar to Guanlong, a more primitive tyrannosauroid from the Late Jurassic of China. By contrast, large-bodied, tyrannosaurines from the last stages of the Cretaceous, like Gorgosaurus, were already triple their masses at similar ages. M. intrepidus suggests that North American tyrannosauroids were restricted to small sizes for a protracted period of ~15 million years and at some point at the Turonian, they embarked on a trend of rapid body size increases, to became the top predators of the Cretaceous.

 

References:

Zanno, L.E, Tucker, R.T., Canoville, A., Avrahami, H.M., Gates, T.A., Makovicky, P.J. (2019), Diminutive fleet-footed tyrannosauroid narrows the 70-million-year gap in the North American fossil record, Communications Biology, DOI: 10.1038/s42003-019-0308-7

On Pterosaurs and feathers.

Reconstruction of one of the studied anurognathid pterosaurs. Credit: Yuan Zhang/Nature Ecology & Evolution.

Feathers were once considered to be unique avialan structures. Recent studies indicated that non avian dinosaurs, as part of Archosauria, possessed the entirety of the known non keratin protein-coding toolkit for making feathers. Primitive theropods, such as Sinosauropteryx and the tyrannosaurs Dilong and Yutyrannus, and some plant-eating ornithischian dinosaurs, such as Tianyulong and Kulindadromeus, are known from their spectacularly preserved fossils covered in simple, hair-like filaments called ‘protofeathers’.

Other integumentary filaments, termed pycnofibres, has been reported in several pterosaur specimens, but there is still a substantial disagreement regarding their interpretation. J. Yang and colleagues described two specimens of short-tailed pterosaurs (NJU–57003 and CAGS–Z070) from the Middle-Late Jurassic Yanliao Biota, in northeast China (around 165-160 million years ago) with preserved structural fibres (actinofibrils) and four different types of pycnofibres. The specimens resemble Jeholopterus and Dendrorhynchoides, but they are relatively small.

 

Drawing of of (a) NJU–57003 and (b) CAGS–Z070 with skeletal element identification, outline of
preserved integument, and distribution of the four types of pycnofibres. From Yang et al., 2018.

Types 1 and 4 of pycnofibres occur in both specimens, but types 2 and 3 occur only in CAGS–Z070. This may reflect original biological differences or differences in the taphonomy of the two specimens. The pterosaur type 1 filaments resemble monofilaments in the ornithischian dinosaurs Tianyulong and Psittacosaurus and the coelurosaur Beipiaosaurus. The pterosaur type 2 filaments resemble the brush-like bundles of filaments in the coelurosaurs Epidexipteryx and Yi. Type 3 filaments resemble bristles in modern birds, but surprisingly do not correspond to any reported morphotype in non-avian dinosaurs. The pterosaur type 4 filaments are identical to the radially branched, downy feather-like morphotype found widely in coelurosaurs such as Caudipteryx and Dilong. Functions of these structures could include insulation, tactile sensing, streamlining and colouration (primarily for camouflage and signalling), as for bristles, down feathers and mammalian hairs.

Type 3 filaments (arrows) and similar structures (triangles). Scale bars: 10 mm in a, c and d; 1 mm in b. From Yang et al., 2018

Pterosaurs were winged cousins of the dinosaurs and lived from around 200 million years ago to 66 million years ago. In the early 1800’s, a fuzzy integument was first reported from the holotype of Scaphognathus crassirostris. A recent study on this specimen shows a subset of pycnofibers and actinofibrils. The discovery of integumentary structures in other pterosaurs, such as Pterorhynchus wellnhoferi (another rhamphorhynchoid pterosaur), and these exquisitely preserved pterosaurs from China, suggest that all Avemetatarsalia (the wide clade that includes dinosaurs, pterosaurs and close relatives) were ancestrally feathered.

References:

Yang Z. et al., 2018. Pterosaur integumentary structure with complex feather-like branching. Nature Ecology and Evolution https://doi.org/10.1038/s41559-018-0728-7

Barrett PM, Evans DC, Campione NE. 2015 Evolution of dinosaur epidermal structures. Biol. Lett. 11: 20150229. http://dx.doi.org/10.1098/rsbl.2015.0229

Kai R.K. Jäger, Helmut Tischlinger, Georg Oleschinski, and P. Martin Sander, Goldfuß was right: Soft part preservation in the Late Jurassic pterosaur Scaphognathus crassirostris revealed by reflectance transformation imaging (RTI) and UV light and the auspicious beginnings of paleo-art, https://doi.org/10.26879/713

Craig B. Lowe, Julia A. Clarke, Allan J. Baker, David Haussler and Scott V. Edwards, Feather Development Genes and Associated Regulatory Innovation Predate the Origin of Dinosauria, Mol Biol Evol (2015) 32 (1): 23-28. doi: 10.1093/molbev/msu309

Soft-tissue evidence in a Jurassic ichthyosaur.

Plesiosaurus battling Temnodontosaurus (Oligostinus), front piece the Book of the Great Sea-Dragons by Thomas Hawkins.

In 1811, in Lyme Regis, one of the richest fossil locations in England and part of a geological formation known as the Blue Lias, Mary Anning and her brother Joseph unearthed the skull of an enigmatic ‘sea monster’. A year later, Mary uncovered the torso of the same specimen. The Annings sold the fossil to the Lord of the Manor of Colway, Mr. Henry Henley, for £23. The specimen was described by Sir Everard Home in 1814. Although no name was proposed for the fossil, Home concluded that it represented a transitional form between fish and crocodiles. Later, in 1819, the skeleton was purchased by Karl Dietrich Eberhard Koenig of the British Museum of London who suggested the name Ichthyosaur (“fish lizard”) in 1817.
Ichthyosaurs are extinct marine reptiles that first diversified near the end of the Early Triassic and remained one of the main predators in the Mesozoic ocean until their disappearance near the Cenomanian-Turonian boundary, 30 million years before the end-Cretaceous mass extinction. They had the largest eyes of all vertebrates, sometimes exceeding 25 cm in maximum diameter. They also have one of the earliest records of live-birth in amniotes.
 

Stenopterygius specimen from the Holzmaden quarry. Credit: Johan Lindgren

Stephen Jay Gould said that the ichthyosaur was his favourite example of convergent evolution: “Consider my candidate for the most astounding convergence of all: the ichthyosaur. This sea-going reptile with terrestrial ancestors converged so strongly on fishes that it actually evolved a dorsal fin and tail in just the right place and with just the right hydrological design. These structures are all the more remarkable because they evolved from nothing— the ancestral terrestrial reptile had no hump on its back or blade on its tail to serve as a precursor.”

During the Norian, the evolution of ichthyosaurs took a major turn, with the appearance of the clade Parvipelvia (ichthyosaurs with a small pelvic girdle). They were notably similar in appearance to extant pelagic cruisers such as odontocete whales. An exquisitely fossilized parvipelvian Stenopterygius from the Early Jurassic (Toarcian) of the Holzmaden quarry in southern Germany, indicates that their resemblance with dolphin and whales is more than skin deep.

Structure and chemistry of MH 432 blubber. From Lindgren et. al. 2018.

The specimen (MH 432; Urweltmuseum Hauff, Holzmaden, Germany) reveals endogenous cellular, sub-cellular and biomolecular constituents within relict skin and subcutaneous tissue. The external surface of the body is smooth, and was presumably comparable in life to the skin of extant cetaceans. The histological and microscopic examination of the fossil, evinced a multi-layered subsurface architecture. The approximately 100-μm-thick epidermis retains cell-like structures that are likely to represent preserved melanophores. The subcutaneous layer is over 500 μm thick, and comprises a glossy black material superimposed over a fibrous mat. The anatomical localization, chemical composition and fabric of the subcutaneous material is interpreted as fossilized blubber, a hallmark of warm-blooded marine amniotes.

 

References:

Lindgren, J., Sjövall, P., Thiel, V., Zheng, W., Ito, S., Wakamatsu, K., … Schweitzer, M. H. (2018). Soft-tissue evidence for homeothermy and crypsis in a Jurassic ichthyosaur. Nature. doi:10.1038/s41586-018-0775-x

Motani, R. (2005). EVOLUTION OF FISH-SHAPED REPTILES (REPTILIA: ICHTHYOPTERYGIA) IN THEIR PHYSICAL ENVIRONMENTS AND CONSTRAINTS. Annual Review of Earth and Planetary Sciences, 33(1), 395–420. doi:10.1146/annurev.earth.33.092203.1227

Introducing Macrocollum itaquii.

M. itaquii, the oldest long-necked dino ever found, dating back 225 million years. (Credit: Müller et al 2018)

Sauropodomorphs were the largest land animals ever recorded in the history of life. Additionally to their colossal size, the sauropodomorph bauplan is also characterised by a small head, long neck, barrel-shaped body and columnar limbs. The group was successful and diverse, achieving a worldwide geographical distribution. Nevertheless, the rise of sauropodomorphs is still poorly understood due to the scarcity of well-preserved fossils in early Norian rocks. The Wachholz site (Caturrita Formation), in southern Brazil, is an important window to early Norian land ecosystems. This unit has yielded several sauropodomorphs, including Unaysaurus tolentinoi and the recently described Macrocollum itaquii, the oldest long-necked dinosaur known, that shed light on the rise of the group.

Discovered in 2012, from rocks belonging to the upper part of the Candelaria Sequence constrained as about 225 Ma, the three individuals described as M. itaquii are relatively well preserved. The holotype specimen (CAPPA/UFSM 0001a) consists of an almost complete and articulated skeleton. The two paratype specimens (CAPPA/UFSM 0001b and CAPPA/UFSM 0001c) are both articulated skeletons with one missing a skull and its cervical series. The clustered preservation of the three skeletons also represents the oldest evidence of gregarious behaviour in sauropodomorphs, a pattern seen in other Triassic associations, such as the ‘Plateosaurus bonebed’ from Central Europe, and the Mussaurus remains from the Laguna Colorada Formation, Argentina.

 

Skull of Macrocollum itaquii (From Müller et al 2018)

The generic name combines the Greek word macro (long) and the Latin word collum (neck), referring to the animal’s elongated neck. The specific epithet honours José Jerundino Machado Itaqui, one of the main actors behind the creation of CAPPA/UFSM (Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia/Universidade Federal de Santa Maria).

M. itaquii was only 3.5 meters long and weighed about 101.6 kilograms, and differs from all other known sauropodomorphs in possessing the following characters: antorbital fossa perforated by a promaxillary fenestra; medial margin of the supratemporal fossa with a simple smooth curve at the frontal/parietal suture; proximal articular surface of metacarpal I transversely narrow; acetabulum not fully open; ischiadic longitudinal groove not reaching the caudal half of the ischium; absence of trochanteric shelf on the femur; medial condyle of distal femoral articulation subrectangular in distal view; proximal end of metatarsal II with a straight medial margin.

An artist’s impression of M. itaquii.

In contrast to most Carnian members of the group, the teeth of M. itaquii and other Norian taxa are fully adapted to an omnivore/herbivore diet. The neck elongation may also have provided a competitive advantage for gathering food resources, allowing members of the group to reach higher vegetation. The modifications of the hindlimb of M. itaquii could be related to the progressive loss of cursorial habits.

 

References:

Müller RT, Langer MC, Dias-da-Silva S. 2018, An exceptionally preserved association of complete dinosaur skeletons reveals the oldest long-necked sauropodomorphs. Biol. Lett. 14: 20180633. http://dx.doi.org/10.1098/rsbl.2018.0633

 

 

Introducing Mirarce eatoni, the wonderful winged messenger.

Skeletal reconstruction of Mirarce eatoni showing preserved skeletal elements (white). Illustration: Scott Hartman.

Birds originated from a theropod lineage more than 150 million years ago. By the Early Cretaceous, they diversified, evolving into a number of groups of varying anatomy and ecology. In recent years, several discovered fossils of theropods and early birds have filled the morphological, functional, and temporal gaps along the line to modern birds. Most of these fossils are from the Jehol Biota of northeastern China, dated between approximately 130.7 and 120 million years ago. Among them was the long bony-tailed Jeholornis, only slightly more derived than Archaeopteryx, that lived with Sapeornis, Confuciusornis, and the earliest members of Enantiornithes.

Enantiornithes are the most diverse group of Mesozoic birds. Their remains have been collected on every continent except Antarctica, although their fossil record is particularly poor in North America and limited to the Late Cretaceous. The first probable enantiornithines from North America were collected in the 19th Century, and may be referable to Avisaurus archibaldi. Originally, A. archibaldi was described as a member of a new clade of non-avian theropod dinosaurs, the Avisauridae, the first recognized clade of enantiornithines, defined as “the common ancestor of Neuquenornis volans and Avisaurus archibaldi plus all its descendants”.

Best-preserved cervical and thoracic vertebrae, including the axis of Mirarce (From Atterholt et al., 2018)

The most complete known North American enantiornithine, the so-called “Kaiparowits avisaurid”, was collected in 1992. The specimen was recognized as a new taxon, Mirarce eatoni. Named for its spectacular preservation and level of morphological detail, the holotype (UCMP 139500) of this large, turkey-sized avisaurid enantiornithine is a three-dimensional partial skeleton consisting of several cervical and thoracic vertebrae (including the axis), the pygostyle, almost all phalanges from the left pes and several from the right, a complete humerus, femur, and tarsometatarsus, a partial scapula, coracoid, furcula, and tibiotarsus, as well as fragments of the sternum, radius, ulna, carpometacarpus, and manual phalanges.

The preserved sternal fragment of Mirarce indicates the presence of a well-developed ventral keel, very similar to that observed in Neuquenornis. In modern birds, the narrow furcula and the remige papillae, transfer aerodynamic forces from the feathers to the wing skeleton. These features were also present in Mirarce, and support the hypothesis that at least some lineages of enantiornithines convergently achieved more advanced aerial capabilities by the Late Cretaceous.

Reconstruction of living Mirarce eatoni. Illustration: Brian Engh.

The Enantiornithes have a long evolutionary history, and surviving up to the K–Pg boundary. Several trends have been suggested for the group, including: a general increase in range of body sizes; a greater degree of fusion of compound elements, and the appearance of advanced flight-related features evolved in parallel to the neornithine lineage (like manual reduction, loss of teeth, increase in size of sternal keel). It has been proposed that they were primarily forest dwellers, so they disappeared after the Chicxulub impact triggered widespread destruction of forests.

 

References:

Atterholt J, Hutchison JH, O’Connor JK. (2018) The most complete enantiornithine from North America and a phylogenetic analysis of the Avisauridae. PeerJ 6:e5910 https://doi.org/10.7717/peerj.5910

Daniel J. Field et al. Early Evolution of Modern Birds Structured by Global Forest Collapse at the End-Cretaceous Mass Extinction. Current Biology, published online May 24, 2018; doi: 10.1016/j.cub.2018.04.062

Halloween special VI: Baron Nopcsa and the dinosaurs of Transylvania

The Nopcsa Sacel Castle

Transylvania is mostly known for its myths about vampires. Following the publication of Emily Gerard’s The Land Beyond the Forest (1888), Jules Verne published Le Château des Carpathes (The Castle of the Carpathians) in which Transylvania is described as one of the most superstitious countries of Europe. But of course, the most significant contribution to the development of the Transylvania place myth was Bram Stoker’s Dracula, published in 1897.

Sacel Castle, at the heart of the Hateg region, is the last residence of the Nopcsa family, known as one of the strangest in Transylvania. Among the members of the family, there were governmental counselors and chancellors of the Transylvanian Court, members of the Royal Minister and of the Royal House, and knights of imperial orders. Baron Franz Nopcsa of Felsöszilvás (1877-1933), was one of the most prominent researchers and scholars of his day, and is considered the forgotten father of dinosaur paleobiology.

Baron Nopcsa in Albanian Uniform, 1915

In 1897 Nopcsa became a student of Vienna University and by the age of 22, he presented the first description and paleobiological analysis of one of the Transylvanian dinosaurs before the Vienna Academy of Science: Telmatosaurus transsylvanicus. The holotype, BMNH B.3386, was found in the Haţeg Basin.

The Hateg region, situated at the heart of Transylvania, is the cradle of Romanian civilization, but 70 million years ago it was a tropical island in the Thetys Ocean, noted for the occurrence of aberrant, endemic, and dwarfed fauna. In 1914, Nopcsa theorized that the “limited resources” found on islands have an effect of “reducing the size of animals” over the generations. Nopcsa noted several palaeobiological features in support of his views, including what he perceived as the common presence of pathological individuals, and considered this condition a reasonable result of the ecologically impoverished and stressed environment inhabited by this fauna. The recognition of ameloblastoma in a Telmatosaurus dentary discovered from the same area represents the best documented case of pathological modification identified in Transylvanian dinosaurs.

Doda, left, and Nopcsa, circa 1931. They spent nearly 30 years together. (Hungarian Natural History Museum)

Nopcsa continued to do collecting in the Haţeg Basin, at least until the beginning of the First World War. Among the fossils that Nopcsa studied were the duck-billed Telmatosaurus transylvanicus, the bipedal and beaked Zalmoxes robustus, the armored Struthiosaurus transylvanicus, and the sauropod Magyarosaurus dacus. In addition, he made extensive travels across much of Europe to visit palaeontological museums and to meet fellow scientists. In his field trips Nopcsa was now accompanied by Elmas Doda Bajazid, whom Nopcsa met in Albania and convinced to become his secretary. The men spent nearly 30 years togheter.

On 25 April 1933, Nopcsa’s body and that of his secretary Bajazid were found at their Singerstrasse residence. Nopcsa left a letter to the police: ”The motive for my suicide is a nervous breakdown. The reason that I shot my longtime friend and secretary, Mr Bayazid Elmas Doda, in his sleep without his suspecting at all is that I did not wish to leave him behind sick, in misery and without a penny, because he would have suffered too much. I wish to be cremated.”

 

References:

David B. Weishampel & Oliver Kerscher (2012): Franz Baron Nopcsa, Historical Biology: An International Journal of Paleobiology, DOI:10.1080/08912963.2012.689745

CSIKI, Z. & BENTON, M.J. (2010): An island of dwarfs – Reconstructing the Late Cretaceous Haþeg palaeoecosystem. Palaeogeography, Palaeoclimatology, Palaeoecology 293: 265 – 270 doi:10.1016/j.palaeo.2010.05.032

Dumbravă, M. D. et al. A dinosaurian facial deformity and the first occurrence of ameloblastoma in the fossil record. Sci. Rep. 6, 29271; doi: 10.1038/srep29271 (2016).

 

 

Introducing Dynamoterror dynastes, the powerful terror ruler.

Frontals of Dynamoterror dynastes in rostral view. From McDonald et al., 2018. (Scale bars = 5 cm)

Tyrannosauroidea is a relatively derived group of theropod dinosaurs more closely related to birds than to other large theropods such as allosauroids and spinosaurids. The clade originated in the Middle Jurassic, approximately 165 million years ago, and for most of their evolutionary history, tyrannosauroids were mostly small-bodied animals that only reached gigantic size during the final 20 million years of the Cretaceous. Until recently, all tyrannosaurs fossils were limited to Asia and North America, but the latest discoveries suggest a more cosmopolitan distribution during their early evolution.

All tyrannosaurs were bipedal predators characterized by premaxillary teeth with a D-shaped cross section, fused nasals, extreme pneumaticity in the skull roof and lower jaws, a pronounced muscle attachment ridge on the ilium, and an elevated femoral head. The clade was a dominant component of the dinosaur faunas of the American West shortly after the emplacement of the Western Interior Seaway (about 99.5 Mya).

Paleogeography of North America during the late Campanian Stage of the Late Cretaceous (∼75 Ma). From Sampson et al., 2010

Dynamoterror dynastes, the most recent taxon described from the lower Campanian of northwestern New Mexico, provides additional data on the morphology and diversity of early tyrannosaurines in Laramidia. The new specimen lived during the Late Cretaceous period, approximately 78 million years ago. The name derived from Greek word dynamis (“power”) and the Latin word terror. The specific name is a Latin word meaning “ruler. Dynamoterror was collected in San Juan County, New Mexico, and is the first associated tyrannosaurid skeleton reported from the Menefee Formation.

The holotype (UMNH VP 28348) is an incomplete associated skeleton including the left and right frontals, four fragmentary vertebral centra, fragments of dorsal ribs, right metacarpal II, supraacetabular crest of the right ilium, unidentifiable fragments of long bones, phalanx 2 of left pedal digit IV, and phalanx 4 of left pedal digit IV. The right and left frontals both are incomplete; the dimensions of the right frontal are similar to a subadult specimen of Tyrannosaurus rex, suggesting that UMNH VP 28348 represents a subadult or adult individual. The reconstructed skull roof of Dynamoterror present several tyrannosaurine features, such as large supratemporal fossae and a tall sagittal crest on the frontals, providing an expanded attachment area for enormous jaw-closing muscles.

 

References:

McDonald AT, Wolfe DG, Dooley AC Jr. (2018) A new tyrannosaurid (Dinosauria: Theropoda) from the Upper Cretaceous Menefee Formation of New Mexico. PeerJ 6:e5749 https://doi.org/10.7717/peerj.5749

Brusatte SL, Norell MA, Carr TD, Erickson GM, Hutchinson JR, et al. (2010) Tyrannosaur paleobiology: new research on ancient exemplar organisms. Science 329: 1481–1485. doi: 10.1126/science.1193304

Sampson SD, Loewen MA, Farke AA, Roberts EM, Forster CA, Smith JA, et al. (2010) New Horned Dinosaurs from Utah Provide Evidence for Intracontinental Dinosaur Endemism. PLoS ONE 5(9): e12292. https://doi.org/10.1371/journal.pone.0012292

 

 

 

 

 

 

 

 

 

 

 

 

Forgotten women of paleontology: Irene Crespin

Irene Crespin (1896-1980)

Irene Crespin was born on November 12, 1896, in Kew, Victoria, Australia. In her memories, she wrote that her interest in Palaeontology began early in her life, when she was one of the first students to attend the Mansfield High School in northeastern Victoria. The head master of for a short period was the eminent Australian geologist Charles Fenner.

In 1919, she graduated with a B.A. from the University of Melbourne. In 1927 she joined the Commonwealth Government as Assistant Palaeontologist to Frederick Chapman at the National Museum of Victoria. Chapman was an authority on Foraminifera and was president of the Royal Society of Victoria. About her time at the Museum she wrote: “In the early days, we passed through the depression era. Our salaries were reduced overnight. I was reduced to six pounds a week. They were difficult times for us all. One would walk a long distance to save a threepenny tram fare.”

Dr Irene Crespin with W. Baragwanath, Secretary of Mines for Victoria, probably visiting a Cooksonia plant site, c. 1927 (From Turner 2007)

In 1936, Crespin succeeded Chapman as Commonwealth Palaeontologist. On February 10th, she was transferred from the National Museum, Melbourne to join the Commonwealth Geological Adviser, Dr. W.G. Woolnough, in Canberra. About her new position she wrote: “Of course, being a woman, and despite the tremendous responsibility placed upon me with the transfer to Canberra, I was given a salary of about half of that which Chapman received. Later the Chairman of the Public Service Board told me that I was being put on trial.”

She becoming greatly interested in the Tertiary microfaunas, and for some time she was the only professional micropaleontologist on the Australian mainland. Her research took her all over Australia. In 1939, she received permission from the Minister of the Interior to visit Java and Sumatra to discuss the problems of Tertiary correlation in the Netherlands East Indies with Papua and New Guinea.

Crespin’s photo of her aeroplane and crew on an overseas trip to Java, Indonesia, 1939 (From Turner 2007)

Crespin was well respected internationally and was a regular participant in national and international scientific conferences. In 1953, many of her books and specimens were destroyed as a result of a fire in the Canberra offices. The same year, she received Queen Elizabeth II’s coronation medal. In 1957 she was president of the Royal Society of Canberra, and was awarded with the Clarke medal of the Royal Society of New South Wales.

During her career she published 86 papers as sole author and more 22 in collaboration with other scientists. She was made an honorary fellow of the Royal Microscopical Society, London, in 1960. She became an honorary member of the Australian and New Zealand Association for the Advancement of Science in 1973. She died in Canberra, on January 2, 1980.

References:

Turner, S. (2007). Invincible but mostly invisible: Australian women’s contribution to geology and palaeontology. Geological Society, London, Special Publications, 281(1), 165–202. doi: 10.1144/sp281.11

Crespin, Irene (1975). “Ramblings of a micropalaeontologist”. BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS.

 

Introducing Jinguofortis perplexus.

Photograph of main slab of J. perplexus (Credit: Wang et al., 2018)

Birds originated from a theropod lineage more than 150 million years ago. By the Early Cretaceous, they diversified, evolving into a number of groups of varying anatomy and ecology. In recent years, several discovered fossils of theropods and early birds have filled the morphological, functional, and temporal gaps along the line to modern birds. Most of these fossils are from the Jehol Biota of northeastern China, dated between approximately 130.7 and 120 million years ago. The Jehol Biota provides an incredibly detailed picture of early birds, including Jeholornis, slightly more derived than Archaeopteryx, that lived with Sapeornis, Confuciusornis, and the earliest members of Enantiornithes and Ornithuromorpha. The clade Ornithothoraces (characterized by a keeled sternum, elongate coracoid, narrow furcula, and reduced hand) along with Jeholornithiformes, Confuciusornithiformes and Sapeornithiformes, form the clade Pygostylia. Basal members of this clade are essential to understand the evolution of the modern avian bauplan. The trait that gives the group its name is the presence of a pygostyle, a set of fused vertebrae at the end of the tail.

Jinguofortis perplexus gen. et sp. nov., from the Early Cretaceous of China, exhibits a mosaic combination of plesiomorphic nonavian theropod features like a fused scapulocoracoid and more derived traits, including the earliest evidence of reduction in manual digits among birds. The generic name is derived from “jinguo” (Mandarin), referring to female warrior, and “fortis” for brave (Latin). The specific name is derived from Latin “perplexus,” and highlights the combination of plesiomorphic and derived features present in the holotype specimen.

Holotype of J. perplexus. (Scale bar, 5 cm.) From Wang et al., 2018.

The holotype (IVPP V24194) was collected near the village of Shixia, Hebei Province, China. Biostratigraphic correlation confirms that the fossil-bearing horizon belongs to the Lower Cretaceous Dabeigou Formation of the Jehol Biota (127 ± 1.1 Ma). The holotype of Jinguofortis is subadult or adult given the bone histology, the presence of a fused carpometacarpus, tarsometatarsus, and pygostyle. The body mass estimated is 250.2 g, the wing span is 69.7 cm, with a wing area of 730 cm2.

Jinguofortis exhibits the following features: dentary with at least six closely packed teeth; scapula and coracoid fused into a scapulocoracoid in the adult; sternum ossified; deltopectoral crest of humerus large and not perforated; minor metacarpal strongly bowed caudally; minor digit reduced with manual phalangeal formula of 2–3-2; metatarsals III and IV subequal in distal extent; pedal phalanx II-2 with prominent heel proximally; and forelimb 1.15 times longer than hindlimb. The highly vascularized fibro-lamellar bone tissue indicates that Jinguofortis grew rapidly in early development, but the growth rate had slowed substantially by the time of death. The histology of Jinguofortis is comparable to that of Chongmingia and Confuciusornis, suggesting a similar growth pattern shared among these basal pygostylians. The phylogenetic analysis recovered Jinguofortis as the sister to Chongmingia. The clade uniting these two specimens is Jinguofortisidae, and constitutes the second most basal pygostylian lineage.

Forelimb of Jinguofortis. (A) Photograph. (B) Line drawing. (Scale bar, 1 cm.) From Wang et al., 2018.

Early avian flight clearly underwent a series of evolutionary experiments, as demonstrated by the diverse combination of plesiomorphic and derived features found among early extinct birds. The most striking primitive feature present in the flight apparatus of Jinguofortis is the fused scapulocoracoid, present predominantly in nonavian theropods. The convergently evolved scapulocoracoid in jinguornithids and confuciusornithiforms suggests that these basal clades likely reacquired a similar level of osteogenesis (or gene expression) present in their nonavian theropod ancestors.

 

References:

Wang, M., Stidham, T. A., & Zhou, Z. (2018). A new clade of basal Early Cretaceous pygostylian birds and developmental plasticity of the avian shoulder girdle. Proceedings of the National Academy of Sciences, 201812176. doi:10.1073/pnas.1812176115