The Forest Out of Time

An artist’s impression of Antarctica as a swampy rainforest between 92m and 83m years ago. (Credit: Alfred-Wegener-Institut/James McKay)

 

Past fluctuations in global temperatures are crucial to understand Earth’s climatic evolution. During the mid-Cretaceous, Earth’s climate was extraordinarily warm with temperatures in the tropics as high as 35 degrees Celsius, particularly during the Turonian to Santonian stages (93.9–83.6 Ma), with increasingly high sea levels and numerous epicontinental seas. The interval was characterized by extensive deposition of organic carbon (OC) rich black shales across a wide range of marine settings. Because marine proxies dominate records of past temperature reconstructions, our understanding of continental climate is relatively poor. Now, researchers from the UK and Germany discovered evidence of a temperate rainforest in West Antartica. The new finding offers a window into the terrestrial conditions of the extreme southern latitudes during this period.

The evidence comes from a core of sediment drilled into the seabed near the Pine Island and Thwaites glaciers in West Antarctica. One section of the core revealed a network of fossil plant roots, and countless traces of pollen and spores from plants, including the first remnants of flowering plants ever found at these high Antarctic latitudes. Pollen assemblage is dominated by the conifer tree families Podocarpaceae and Araucariaceae. The abundant tree ferns includes Cyathea. The presence of Sterisporites antiquasporites (Bryophyta, Sphagnum) suggest the temporary existence of a peat swamp. This coincides with increasing Peninsulapollis pollen.

 

West Antarctica. Image: Unsplash/Henrique Setim

Pollen and other palynomorphs proved to be an extraordinary tool to palaeoenvironmental reconstruction. In 1921, Gunnar Erdtman, a Swedish botanist, was the first to suggest this application for fossil pollen study. Like spores, pollen grains reflects the ecology of their parent plants and their habitats and provide a continuous record of their evolutionary history. Based on the palynomorph assemblage, the researchers found that the annual mean air temperature was around 13 degrees Celsius, and the average temperature of the warmest summer month was 18.5°C, whereas the amount and intensity of rainfall were similar to those in today’s Wales.

The mid-Cretaceous was an interval of intense climatic, tectonic and biotic changes across Gondwana. The break-up of the supercontinent and the rise of angiosperms caused a global floral turnover. Antarctica is particularly important because it preserves rock sequences that record the climate during the break-up of the supercontinent and the climate changes during the onset of continental-scale glaciation.

 

References:

Klages, J.P., Salzmann, U., Bickert, T. et al. Temperate rainforests near the South Pole during peak Cretaceous warmth. Nature 580, 81–86 (2020). https://doi.org/10.1038/s41586-020-2148-5

Forster, A. et al. Tropical warming and intermittent cooling during the Cenomanian/Turonian Oceanic Anoxic Event (OAE 2): sea surface temperature records from the equatorial Atlantic. Paleoceanography 22, PA1219 (2007). DOI:10.1029/2006PA001349

Introducing Dineobellator notohesperus

Life reconstruction of Dineobellator notohesperus. Artwork by Sergey Krasovskiy

 

The iconic Velociraptor mongoliensis, described by Osborn in 1924, belongs to the Dromaeosauridae, a family of highly derived small to mid-sized theropod dinosaurs closely related to birds. Their fossils have been found in North America, Europe, Africa, Asia, South America and Antarctica. They first appeared in the mid-Jurassic Period, but their fossil record in North America is very poor near the time of their extinction prior to the Cretaceous-Paleogene boundary. The group is characterized by the presence of long, three-fingered forelimbs that ended in sharp, trenchant claws and a tail stiffened by the elongated prezygapophyses.

The description of Dineobellator notohesperus, a new specimen discovered in 2008 in New Mexico, offers a glimpse into the biodiversity of Dromaeosaurids at the end of the Cretaceous. The generic name is derived from the Navajo word Diné, in reference to the people of the Navajo Nation, and the Latin suffix bellator, meaning warrior. The specific name is derived from the Greek word noto, meaning southern, or south; and the Greek word hesper, meaning western.

 

Skeletal reconstruction of Dineobellator notohesperus. From Jasinski et al., 2020

 

The holotype (SMP VP-2430), similar in size to Velociraptor and Saurornitholestes, includes elements of the skull, axial, and appendicular skeleton. The nearly complete right humerus measures 185.78 mm, with an estimated total length of 215 mm. The presence of quill knobs in Dineobellator provides further evidence for feathers throughout Dromaeosauridae. This new specimen co-existed with numerous other theropods, including caenagnathids, ornithomimids, troodontids, and tyrannosaurids.

Dineobellator exhibits some features in the forelimbs that suggest greater strength capabilities in flexion, in conjunction with a relatively tighter grip strength in the manual claws, while the possession of opisthocoelous proximal caudal vertebrae may have increased the agility of Dineobellator and thus may have implications for its predatory behavior, particularly with respect to the pursuit of prey.

 

References:

Jasinski, S.E., Sullivan, R.M. & Dodson, P. New Dromaeosaurid Dinosaur (Theropoda, Dromaeosauridae) from New Mexico and Biodiversity of Dromaeosaurids at the end of the Cretaceous. Sci Rep 10, 5105 (2020). https://doi.org/10.1038/s41598-020-61480-7

Senter, P., Kirkland, J. I., DeBlieux, D. D., Madsen, S. & Toth, N. New dromaeosaurids (Dinosauria: Theropoda) from the Lower Cretaceous of Utah, and the evolution of the dromaeosaurid tail. PLoS One 7, e36790 (2012). https://doi.org/10.1371/journal.pone.0036790

Osborn, Henry F. (1924a). “Three new Theropoda, Protoceratops zone, central Mongolia”. American Museum Novitates. 144: 1–12. http://hdl.handle.net/2246/3223

 

Introducing Asteriornis maastrichtensis

 

Three-dimensional image of the skull of Asteriornis maastrichtensis.
Image credit: Daniel J. Field, University of Cambridge

The earliest diversification of extant birds (Neornithes) occurred during the Cretaceous period. After the mass extinction event at the Cretaceous-Paleogene (K-Pg) boundary, the Neoaves, the most diverse avian clade, suffered a rapid global expansion and radiation. A genome-scale molecular phylogeny indicates that nearly all modern ordinal lineages were formed within 15 million years after the extinction, suggesting a particularly rapid period of both genetic evolution and the formation of new species. Today, with more than 10500 living species, birds are the most species-rich class of tetrapod vertebrates. The description of a new neornithine from the Late Cretaceous of Belgium shed new light on the evolution of birds.

Asteriornis maastrichtensis is a small member of the clade Pangalloanserae, the group that includes Galliformes and Anseriformes, with an estimated body weight of about 400 grams. The holotype (NHMM, 2013 008) includes a nearly complete, articulated skull with mandibles, and associated postcranial remains preserved in four blocks. The new specimen, dated between 66.8 and 66.7 million years ago, was collected in 2000 by Maarten van Dinther. The generic name is derived from the name of the Asteria, the Greek goddess of falling stars, and the Greek word ornis for bird. The specific name maastrichtensis honors the provenance of the holotype, the Maastricht Formation (the type locality of the Late Cretaceous Maastrichtian stage).

Artist’s reconstruction of Asteriornis maastrichtensis.
Illustration: Phillip Krzeminski

Asteriornis exhibits caudally pointed nasals that overlie the frontals and meet at the midline of the skull, and a slightly rounded, unhooked tip of the premaxilla. The new specimen reveals a previously undocumented combination of ‘galliform’ and ‘anseriform’ features that emphasizes the modular nature of the skull and bill of crown birds. The narrow and elongate hindlimbs and provenance from nearshore marine sediments suggest that Asteriornis might have had a shorebird-like ecology.

 

References:

Field, D.J., Benito, J., Chen, A. et al. Late Cretaceous neornithine from Europe illuminates the origins of crown birds. Nature 579, 397–401 (2020). https://doi.org/10.1038/s41586-020-2096-0

Introducing Thanatotheristes degrootorum, the Reaper of Death

Thanatotheristes degrootorum. Illustration by Julius Csotonyi

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. To explain their geographic dispersal through Laurasia, one phylogenetic hypothesis suggested a scenario where basal tyrannosaurids (i.e., albertosaurines and Daspletosaurus) occurred in northern locations (Alberta and Montana) and derived tyrannosaurids (i.e. Bistahieversor, Lythronax, and Teratophoneus) occurred farther south (New Mexico and Utah), with the Tyrannosaurus evolving from the southern group during the Maastrichtian.

The recently described Thanatotheristes degrootorum, from the middle Campanian of the Foremost Formation of Alberta, Canada, is the oldest tyrannosauroid known from Canada and is approximately 2.5 million years older than Gorgosaurus libratus and Daspletosaurus torosus from the Oldman and Dinosaur Park formations. This new specimen provides a new tool to understand the evolution and paleogeographic distribution of Tyrannosauridae.

Jaw bones of Thanatotheristes degrootorum. Image credit: Jared Voris

The holotype (TMP 2010.5.7) includes the right maxilla, right jugal, right postorbital, right surangular, right quadrate, right laterosphenoid, left frontal, and both dentaries. The presence of a well-developed ornamentation on the maxilla suggests the individual was probably sexually mature. A referred specimen (TMP 2018.016.0001) is based on a partial right maxilla from a subadult individual, and it was found approximately 10 km northeast of Hays, Alberta. The name derived from Thanatos the Greek god of death, and theristes (Greek), harvester or reaper. The specific name honors John and Sandra De Groot, who discovered the holotype specimen.

The new taxon is one of the earliest tyrannosaurid from North America, and is roughly equivalent in age to Dynamoterror dynastes from the Menefee Formation of northern New Mexico, but is slightly younger than Lythronax argestes from the Wahweap Formation of southern Utah.

Thanatotheristes skull. Image credit: Jared Voris

Phylogenetic analysis suggests that Thanatotheristes is most closely related to Daspletosaurus. Together, they form the clade Daspletosaurini, a group of long and deep-snouted tyrannosaurines. Thanatotheristes differs from Daspletosaurus in several characters. For instante, in Thanatotheristes the contact surface for the jugal on the postorbital is braced by a robust ridge that extends to the posterior margin of the postorbital. Furthermore, Thanatotheristes lacks two synapomorphies diagnostic for Daspletosaurus. First, the posterior bifurcation of the antotic crest of the laterosphenoid is an indistinct ridge rather than a prominent shelf-forming crest. Second, the symphyseal surface of the dentary only displays low anteroposterior ridges and lacks large interlocking bony projections.

The addition of more basal tyrannosaurid clades reveals that at least five major lineages evolved within Tyrannosauridae, with different skeletal morphotypes linked to differences in paleoecology, such as prey composition or hunting/feeding strategies.

 

References:

Voris, J.T., Therrien, F., Zelenitsky, D.K., Brown, CM., A new tyrannosaurine (Theropoda:Tyrannosauridae) from the Campanian Foremost Formation of Alberta, Canada, provides insight into the evolution and biogeography of tyrannosaurids, Cretaceous Research, https://doi.org/10.1016/j.cretres.2020.104388.

 

Climate Change and the legacy of the Challenger expedition

SEM images of selected planktonic foraminifera specimens; (i) T. trilobus (Tara), (j) G. ruber (Tara), (k) G. ruber (Challenger), (l) G. bulloides (Challenger), (m,n) G. ruber test cracked to reveal wall texture (Tara), (o,p) G. ruber test cracked to reveal wall texture (Challenger). From Fox et al., 2020.

It all began in 1868, with British naturalist William B. Carpenter and Sir Charles Wyville Thomson, Professor of Natural History at Edinburgh University. They persuaded the Royal Society of London to sponsor a prolonged voyage of exploration across the oceans of the globe. But it was not until 1872 that Royal Society of London obtained the use of the HSM Challenger from the Royal Navy. The ship was modified for scientific work with separate laboratories for natural history and chemistry. The cost of expedition was £200,000 – about £10 million in today’s money. The expedition was led by Captain George Nares and the scientific work was conducted by Wyville Thomson assisted by Sir John Murray, John Young Buchanan, Henry Nottidge Moseley, and the German naturalist Rudolf von Willemoes-Suhm. From 1872 to 1876, Murray developed a pioneering device which could register the temperature of the ocean at great depths, and assisted in the collection of marine samples. After the dead of Thomson in 1882, John Murray became director and edited the Challenger Expedition Reports. 

The science and ship crew of the HMS Challenger in 1874.

 
The planktonic foraminifera collected during the HMS Challenger expedition are part of the historical collection of the Natural History Museum, London. Their importance as tool for paleoclimate reconstruction was recognized early in the history of oceanography. The samples collected almost 150 years ago provide an extraordinary opportunity to understand the effects of one of the most urgent questions of our time with regards to anthropogenic environmental change: ocean acidification. 
 
Planktonic foraminifera are a group of marine zooplankton with a shell composed of secrete calcite or aragonite, with no internal structures and different patterns of chamber disposition (trochospiral, involute trochospiral and planispiral growth); with perforations and a variety of surface ornamentations like cones, short ridges or spines. Their shells take up chemical signals from the sea water, in particular isotopes of oxygen and carbon. Over millions of years, these skeletons accumulate in the deep ocean to become a major component of biogenic deep-sea sediments. By comparing the sediment samples from the HMS Challenger Expedition (1872–1876) with the recent Tara Oceans expedition material (2009–2016), the researchers found that the composition of the planktonic foraminifera has changed significantly since the pre-industrial period, and revealed that all modern specimens had up to 76% thinner shells than their historic counterparts.
 
 
 

Nano-CT representative reconstructions and measurements for Neogloboquadrina dutertrei from Tara (a–c), and Challenger (d–f). From Fox et al., 2020.

Ocean acidification affects the biogeochemical dynamics of calcium carbonate, organic carbon, nitrogen, and phosphorus and interferes with a range of processes including growth, calcification, development, reproduction and behaviour in a wide range of marine organisms like planktonic coccolithophores, foraminifera, echinoderms, corals, and coralline algae. Additionaly, ocean acidification can intensify the effects of global warming, in a dangerous feedback loop. Since the Industrial Revolution the pH within the ocean surface has decreased ~0.1 pH and is predicted to decrease an additional 0.2 – 0.3 units by the end of the century. 

After the World War II, the impact of human activity on the global environment dramatically increased. This period associated with very rapid growth in human population, resource consumption, energy use and pollution, has been called the Great Acceleration. In the coming decades, the ocean’s biogeochemical cycles and ecosystems will become increasingly stressed by ocean warming, acidification and deoxygenation. This scenario underlines the urgency for immediate action on global carbon emission reductions.

 

References:

Fox, L., Stukins, S., Hill, T. et al. Quantifying the Effect of Anthropogenic Climate Change on Calcifying Plankton. Sci Rep 10, 1620 (2020). https://doi.org/10.1038/s41598-020-58501-w

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

Wyville Thompson, C. The Voyage of the “Challenger”. The Atlantic. 2 volumes (1878).

Dohrn, Anton. (1895). The Voyage of HMS “Challenger” A Summary of the Scientific Results. http://doi.org/10.1038/052121a0

 

 

From Mantell to de Ricqlès: A brief history of Paleohistology

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

The aim of Paleohistology is the study of the microstructure of fossilized skeletal tissues. Despite that the organic components of mineralised tissues decay after death, the inorganic components of bone preserve the spatial orientation of organic components such as osteocyte lacunae, vascular canals, and collagen fibres.

The techniques for the microscopic study of biological tissues began in 1828, when two British scientists, Henry Witham and William Nicol, experimented by grinding sheets of petrified tree trunk into traslucents sheets so that they could viewed under the microscope. Few years later the new technique was applied to fossil vertebrates by Agassiz. In 1849, John Thomas Quekett published his most important paper on the histological structure of bone in mammals, birds, reptiles, and fish. He described vascular canals, lacunae and canaliculi, and trabecular endosteal bone.

Dorsal dermal spine of the Hylaerosaurus (From Mantell, 1850a. Plate XXVII)

The next important advance was the first clear description of dinosaur bone microstructure: Hylaerosaurus made by British paleontologist Gideon Mantell in 1850. In his work, Mantell provides a drawing of a thin section from a “dorsal dermal spine” of Hylaerosaurus. The same year, Mantell described a transverse thin section from a humerus of Pelorosaurus, and notes that the bone exhibits an “intimate structure beautifully preserved; the bone cells, and Haversian canals, are as distinct as in recent bones.” In 1871, John Phillips described the structure of pterosaur bones from the Stonesfield ‘Slate’ (Bathonian, Middle Jurassic, England) and noted that pterosaur bones contained longitudinal “Haversian canals” and figured “lacunae… with many short excurrent somewhat branched tubules”.

Detail of the humerus of Vegavis iaai (MACN-PV 19.748) in polarised light. Scale = 1 mm. (From G, Marsà et al., 2017)

A century later, the introduction of hard plastic resins, the development of tungsten carbide microtome blades, the use of very thin diamond-edged saw blades, and the examination of bone tissue with surgically implanted orthopedic devices fostered new methods for studying the histology of fully mineralized bone.

Armand de Ricqlès, in the 1960s and 1970s, observed that paleohistological features could be correlated with growth rates and thus could indirectly shed light on the thermal physiology of extinct organisms. He based his conclusions on the neontological observations of Rodolfo Amprino. Quantitative studies confirmed that avascular bone is deposited more slowly than vascular bone, and radial bone is deposited faster than laminar bone. De Ricqlès early histological examinations of dinosaur bones suggested that they did not grow in a manner similar to extant cold-blooded reptiles (which deposit poorly vascularized cortical bone, interrupted by many lines of arrested growth). On the contrary, the evidence indicated that dinosaurs had a physiology that more closely approximated that of extant, fast-growing, endothermic birds. He included pterosaurs in a discussion on reptile bone histology and emphasised the structural similarities with bird bones such as the large diaphyseal medullary cavities enclosed by a dense cortex, with spongiosa in the epiphyseal region. The studies conducted by de Ricqlès opened a new path for paleohistology and his work continues to influence the field today.

Recent

References:
Bailleul AM, O’Connor J, Schweitzer MH. 2019. Dinosaur paleohistology: review, trends and new avenues of investigation. PeerJ 7:e7764 https://doi.org/10.7717/peerj.7764

Quekett J. (1849) On the intimate structure of bone, as composing the skeleton, in the four great classes of animals, viz., mammals, birds, reptiles, and fishes, with some remarks on the great value of the knowledge of such structure in determining the affinities of minute fragments of organic remains. Transactions of the Microscopical Society of London. 1849;2(1):46–58. doi: 10.1111/j.1365-2818.1849.tb05102.x.
Mantell Gideon Algernon (1850) XVII. On a dorsal dermal spine of the Hylæosaurus, recently discovered in the strata of Tilgate Forest140 Phil. Trans. R. Soc. http://doi.org/10.1098/rstl.1850.0018

Mantell Gideon Algernon (1850b) XVI. On the pelorosaurus; an undescribed gigantic terrestrial reptile whose remains are associated with those of the iguanodon and other saurians in the strata of Tilgate Forest, in Sussex140Phil. Trans. R. Soc. http://doi.org/10.1098/rstl.1850.0017

De Ricqlès (1969) De Ricqlès A. L’histologie osseuse envisagée comme indicateur de la physiologie thermique chez les tétrapodes fossiles. Comptes Rendus Hebdomadaires des Séances de l’Academie des Sciences, Serie D: Sciences Naturelles. 1969;268:782–785

“Lucifer’s Hammer killed the dinosaurs”

Lucifer’s Hammer Hardcover (1977)

The end of the Mesozoic era at ca. 66 million years ago (Ma) is marked by one of the most severe biotic crisis in Earth’s history: the Cretaceous-Paleogene (K-Pg) mass extinction. During the event, three-quarters of the plant and animal species on Earth disappeared, including non-avian dinosaurs, pterosaurs, marine reptiles, ammonites, and planktonic foraminifera. Two planetary scale disturbances were linked to this mass extinction event: the eruption of the Deccan Traps large igneous province, and the collision of an asteroid of more than 10 km in diameter with the Yucatan Peninsula.

“Lucifer’s Hammer”, written by Larry Niven and Jerry Pournelle, was the first major science fiction novel to try to deal realistically with the planetary emergency of an impact event. It was published in 1977. Almost at the same time, the discovery of anomalously high abundance of iridium and other platinum group elements in the Cretaceous/Palaeogene (K-Pg) boundary led to the hypothesis that an asteroid collided with the Earth and caused one of the most devastating events in the history of life.

Gravity anomaly map of the Chicxulub impact structure (From Wikimedia Commons)

“Lucifer’s Hammer killed the dinosaurs,” said US physicist Luis Alvarez, in a lecture on the geochemical evidence he and his son found of a massive impact at the end of the Cretaceous period. A year later, Pemex (a Mexican oil company) identified Chicxulub as the site of this massive asteroid impact. The crater is more than 180 km (110 miles) in diameter and 20 km (10 miles) in depth. The impact released an estimated energy equivalent of 100 teratonnes of TNT, induced earthquakes, shelf collapse around the Yucatan platform, and widespread tsunamis that swept the coastal zones of the surrounding oceans.

The event also produced high concentrations of dust, soot, and sulfate aerosols in the atmosphere. Global forest fires might have raged for months. Photosynthesis stopped and the food chain collapsed. The combination of dust and aerosols precipitated a severe impact winter in the decades after impact. Ocean acidification was the trigger for mass extinction in the marine realm. Acidification affects the biogeochemical dynamics of calcium carbonate, organic carbon, nitrogen, and phosphorus in the ocean and interferes with a range of processes including growth, calcification, development, reproduction and behaviour in a wide range of marine organisms like planktonic coccolithophores, foraminifera, echinoderms, corals, and coralline algae. Additionaly, ocean acidification can intensify the effects of global warming, in a dangerous feedback loop.

The Deccan traps

Early work speculated that the Chicxulub impact triggered large-scale mantle melting and initiated the Deccan flood basalt eruption. Precise dating of both, the impact and the flood basalts, show that the earliest eruptions of the Deccan Traps predate the impact. But, the Chicxulub impact, and the enormous Wai Subgroup lava flows of the Deccan Traps continental flood basalts appear to have occurred very close together in time. Marine volcanism also provides a potential source of oceanic acidification, but a recemt study by Yale University indicates that the sudden ocean acidification was caused by the Chicxulub bolide impact (and not by the volcanic activity) that vaporised rocks containing sulphates and carbonates, causing sulphuric acid and carbonic acid to rain down. The evidence came from the shells of planktic and benthic foraminifera. More recently, a new study focused on carbon cycle modeling and paleotemperature records shows that the Chicxulub impact was the primary driver of the end-Cretaceous mass extinction.The global temperature compilation reveals that ~50% of Deccan Trap CO2 outgassing occurred well before the impact. Additionalty, the Late Cretaceous warming event attributed to Deccan degassing is of a comparable size to small warming events in the Paleocene and early Eocene.

References:
P.M. Hull et al., “On impact and volcanism across the Cretaceous-Paleogene boundary,” Science (2019). Vol. 367, Issue 6475, pp. 266-272 https://science.sciencemag.org/content/367/6475/266

Alvarez, L., W. Alvarez, F. Asaro, and H.V. Michel. 1980. Extraterrestrial cause for the Cretaceous-Tertiary extinction: Experimental results and theoretical interpretation. Science 208:1095–1108.

Michael J. Henehan el al., “Rapid ocean acidification and protracted Earth system recovery followed the end-Cretaceous Chicxulub impact,” PNAS (2019). www.pnas.org/cgi/doi/10.1073/pnas.1905989116

Top fossil discoveries of 2019.

This was a turbulent year. The recent fires at Amazonas, Gran Canaria (Spain), Australia, and Indonesia sparked international outcry. Climate emergency movement took centre stage and Greta Thunberg become a household name as the face of the climate activism. Carl Sagan once said “You have to know the past to understand the present.”As the climate crisis escalates many studies published this year highlights the relation between mass extinctions and climate change.

Nevertheless, 2019 was another remarkable year for paleontology. Among the most striking fossil discoveries are China’s Qingjiang biota that document the Cambrian explosion; the nearly complete skull of Australopithecus anamensis, the oldest known species in a hominid genus that includes Australopithecus afarensis; and the world’s oldest fossilised forest found at an abandoned quarry in Cairo, New York. My top list (with a profound bias towards vertebrate paleontology) includes:

  • Moros intrepidus

Moros intrepidus. Credit: Jorge Gonzalez

Moros intrepidus, a diminutive tyrannosauroid, from Cenomanian-aged terrestrial deposits of western North America. 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. 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.

  • Bajadasaurus pronuspinax

Bajadasaurus pronuspinax gen. et sp. nov., from the Early Lower Cretaceous of Bajada Colorada Formation in Northern Patagonia, Argentina, was discovered in 2013, by a team of paleontologists from CONICET, Fundación Félix de Azara, Universidad Maimónides, and Museo Paleontológico Ernesto Bachmann. The holotype, MMCh-PV 75, includes a nearly complete skull (left maxilla, left lacrimal, both prefrontals, both frontals, both parietals, both postorbitals, both squamosals, left quadratojugal, both pterygoids, both quadrates, supraoccipital, exoccipital-opisthotic complex, basioccipital, basisphenoid, both prootics, both laterosphenoids, both orbitosphenoids, both dentaries, left surangular, both angulars, both splenials, left prearticular, left articular, isolated upper tooth row), both proatlases, atlantal neurapophyses, axis and the fifth cervical vertebra.

  • Iberodactylus andreui

Comparison of the rostrum of Iberodactylus andreui gen. et sp. nov. (MPZ-2014/1) with a cast of a skull of Hamipterus tianshanensis. From Holgado et al., 2019)

Iberodactylus andreui is a pterosaurs from the Lower Cretaceous of Spain. The holotype (MPZ-2014/1) consists of the anterior portion of the rostrum (~198 mm in length), and includes a partially preserved premaxillary crest, and a fragment of the maxillary bone with several fragmentary teeth. The specimen preserved its original 3D shape, although exhibits frequent fractured bones, that added to the eroded bone surfaces, reveal an external thing layer of cortical bone of 1.5 mm. The robustness and height of the premaxillary crest, suggest that MPZ-2014/1 may represent a male specimen. The most striking feature of MPZ-2014/1 is the premaxillary crest. This crest exhibits well-developed elongated, sub-vertical striae and sulci, anteriorly curved, a combination that is quite similar to Hamipterus tianshanensis from the Berriasian-Albian of China.

  • Suskityrannus hazelae

Partial skeleton of Suskityrannus hazelae. Image credit: Virginia Tech.

Suskityrannus hazelae is a small-bodied species phylogenetically intermediate between the oldest, smallest tyrannosauroids and the gigantic, last-surviving tyrannosaurids. The holotype specimen (MSM P4754) includes a partially articulated skull, and fragments of the braincase. The postcranial includes two cervical vertebrae with cervical rib fragments, , a trunk centrum, part of a sacral centrum, and distal portions of left metatarsals II–IV. The paratype (MSM P6178) includes the anterior portion of right dentary; left frontal, partial left postorbital, cervical, trunk, partial sacral and caudal vertebrae; isolated neural arches; partial left scapula; manual ungual fragments; partial pubes, femora, tibiae, fibulae and astragali; partial right pes; and bone fragments.

  • Notatesseraeraptor frickensis

Notatesseraeraptor frickensis at the Sauriermuseum Frick.

Notatesseraeraptor frickensis, from the Late Triassic of Switzerland, is a basal member of Dilophosauridae, a clade that comprises Dilophosaurus, and Cryolophosaurus. The specimen belong to an immature individual of length 2.6–3.0 m, and it was collected in 2006 from Gruhalde clay pit in Frick (Aargau, Switzerland), a place well known for its abundant, articulated Plateosaurus material. The cranium is proportionally long and low as is commonly found in traditional coelophysoid-grade neotheropods. The postcranial skeleton includes two articulated forelimbs, 13 dorsal, four sacral and four proximal caudal vertebrae; cervical, dorsal and sacral ribs; chevrons; gastralia; and even stomach contents ( a well-preserved maxilla of the rhynchocephalian Clevosaurus).

  • Ferrodraco lentoni

Ferrodraco lentoni gen. et sp. nov. holotype. From Pentland et al., Scientific Reports.

Ferrodraco lentoni, from the Winton Formation (Cenomanian–lower Turonian), is the most complete pterosaur specimen ever found in Australia. Discovered in 2017, the holotype specimen AODF 876 (Australian Age of Dinosaurs Fossil) includes a partial skull, five partial neck vertebrae, and bones from both the left and right wings. The wingspan of Ferrodraco was approximately 4 m, with a skull probably reaching 60 cm in length. The generic name comes from the Latin language: ferrum (iron), in reference to the ironstone preservation of the holotype specimen, and draco (dragon). The species name, lentoni, honours former Winton Shire mayor Graham Thomas ‘Butch’ Lenton. Based on several cranial synapomorphies, including the presence of a mandibular groove, smooth and blade-like premaxillary and mandibular crests, and spike-shaped teeth, Ferrodraco falls within the clade Anhangueria. This group has also been recorded in the Early Cretaceous of Brazil, China and England.

  • Adratiklit boulahfa

Isolated cervical vertebra referred to Adratiklit boulahfa. From Maidment et al., 2019.

Adratiklit boulahfa, from the Middle Jurassic of Morocco, is the oldest stegosaur ever found. The holotype (NHMUK PV R37366) of Adratiklit boulahfa is a dorsal vertebra. Referred specimens include three cervical vertebrae (NHMUK PV R37367 and NHMUK R37368, the latter specimen consisting of a series of two articulated bones), a dorsal vertebra (NHMUK PV R37365) and a left humerus (NHMUK PV R37007). Stegosauria is a clade of ornithischian dinosaurs and the closest relative to Ankylosauria; together they form the Eurypoda. These armored dinosaurs were diverse and abundant throughout the Late Jurassic and Cretaceous in Laurasia; but their remains are extremely rare in Gondwana. It has been suggested that Isaberrysaura mollensis from the Jurassic of Argentina might be a stegosaur. Additionally fragmentary discoveries of possible eurypodans have been made in Australia, New Zealand, India and Madagascar, while some eurypodan trackways have been identified in Morocco, Bolivia and Brazil.

  • Gnathovorax cabreirai.

Skull of Gnathovorax cabreirai. From Pacheco et al., 2019

Gnathovorax cabreirai was found in 2014 at the Marchezan site, municipality of São João do Polêsine, Rio Grande do Sul, Brazil. The generic name means “jaws inclined to devour”. The specific name honors Dr. Sérgio Furtado Cabreira, the palaeontologist that found the specimen. The Santa Maria Formation in southern Brazil, comprises a succession of Middle to Late Triassic sedimentary rocks that have been long renowned for their rich tetrapod fossils including one of the oldest (and the best preserved) associations of dinosaur and dinosaur precursor. Gnathovorax lived around 230 million years ago and measured about three meters in length. The holotype (CAPPA/UFSM 0009) is an almost complete and partially articulated skeleton. The skull is almost entirely preserved. Among other characters, Gnathovorax presents three premaxillary teeth; an additonal fenestra between the maxilla and premaxilla contact; two well defined laminae in the antorbital fossa of the maxilla, with a depression between them. The proximal portion of the femur lacks a caudomedial tuber. The tibia equals 90% of the femoral length and there are three phalanges in pedal digit V.

  • Asfaltovenator vialidadi.

Skeletal reconstruction and postcranial anatomy of Asfaltovenator vialidadi, MPEF PV 3440. From Rauhut and Pol, 2019.

Skeletal reconstruction and postcranial anatomy of Asfaltovenator vialidadi, MPEF PV 3440. From Rauhut and Pol, 2019.

Asfaltovenator vialidadi, a new basal tetanuran from the Middle Jurassic of Argentina, shed new ligth on the early radiation of this group. The holotype (MPEF PV 3440) includes an almost complete skull and a partial skeleton. The skull is high and slightly arched, similar to that of other allosauroids and reached 75–80 cm long. The estimated body length of the holotype is 7–8 m, which makes Asfaltovenator comparable in size to the well-known Allosaurus. The phylogenetic analysis of A. vialidadi suggest that Allosauroidea  and Megalosauroidea have a common ancestor that they do not share with coelurosaurs. The new study also suggest that the Pliensbachian-Toarcian extinction event was a potential driver of tetanuran radiation.

  • A postcard from the Cretaceous

Nullotitan glaciaris gen. et sp. nov. Cervical vertebra (MACN Pv 18644) in left lateral (A), dorsal (B), posterior (C), right lateral (D), and longitudinal section (E) views

The Chorrillo Formation ((Upper Cretaceous) in the southern region of the Argentine Patagonia yielded an extraordinare fossil assemblage. Plants, palynomorphs, invertebrates and vertebrates constitutes an amazing window into de Cretaceous. Dinosaur remains include the elasmarian (basal Iguanodontia) Isasicursor santacrucensis gen. et sp. nov; the large titanosaur Nullotitan glaciaris gen. et sp. nov., small Megaraptoridae indet., and fragments of sauropod and theropod eggshells.

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

Gallina, Pablo A., Apesteguía, Sebastián, Canale, Juan I., Haluza, Alejandro (2019), A new long-spined dinosaur from Patagonia sheds light on sauropod defense system, Scientific Reports volume 9, Article number: 1392 DOI: https://doi.org/10.1038/s41598-018-37943-3

Borja Holgado, Rodrigo V. Pêgas, José Ignacio Canudo, Josep Fortuny, Taissa Rodrigues, Julio Company & Alexander W.A. Kellner, 2019, “On a new crested pterodactyloid from the Early Cretaceous of the Iberian Peninsula and the radiation of the clade Anhangueria”, Scientific Reports 9: 4940

Sterling J. Nesbitt et al. A mid-Cretaceous tyrannosauroid and the origin of North American end-Cretaceous dinosaur assemblages. Nature Ecology & Evolution, published online May 6, 2019; doi: 10.1038/s41559-019-0888-0

Marion Zahner; Winand Brinkmann (2019). “A Triassic averostran-line theropod from Switzerland and the early evolution of dinosaurs”. Nature Ecology & Evolution. doi:10.1038/s41559-019-0941-z

Adele H. Pentland et al., Ferrodraco lentoni gen. et sp. nov., a new ornithocheirid pterosaur from the Winton formation (cenomanian-lower turonian) of Queensland, Australia, DOI: 10.1038/s41598-019-49789-4

Maidment, Susannah C. R.; Raven, Thomas J.; Ouarhache, Driss; Barrett, Paul M. (2019-08-16). “North Africa’s first stegosaur: Implications for Gondwanan thyreophoran dinosaur diversity”. Gondwana Research. 77: 82–97. doi:10.1016/j.gr.2019.07.007
Pacheco C, Müller RT, Langer M, Pretto FA, Kerber L, Dias da Silva S. 2019. Gnathovorax cabreirai: a new early dinosaur and the origin and initial radiation of predatory dinosaurs. PeerJ 7:e7963 https://doi.org/10.7717/peerj.7963

Rauhut, Oliver W. M.; Pol, Diego (2019), Probable basal allosauroid from the early Middle Jurassic Cañadón Asfalto Formation of Argentina highlights phylogenetic uncertainty in tetanuran theropod dinosaurs https://www.nature.com/articles/s41598-019-53672-7
Novas, F., Agnolin, F., Rozadilla, S., Aranciaga-Rolando, A., Brissón-Eli, F., Motta, M., Cerroni, M., Ezcurra, M., Martinelli, A., D’Angelo, J., Álvarez-Herrera, G., Gentil, A., Bogan, S., Chimento, N., García-Marsà, J., Lo Coco, G., Miquel, S., Brito, F., Vera, E., Loinaze, V., Fernandez, M., & Salgado, L. (2019). Paleontological discoveries in the Chorrillo Formation (upper Campanian-lower Maastrichtian, Upper Cretaceous), Santa Cruz Province, Patagonia, Argentina. Revista del Museo Argentino de Ciencias Naturales, 21(2), 217-293.

Christmas edition: Geologizing with Dickens, part III.

Charles Dickens at his desk, by George Herbert Watkins (National Portrait Gallery. From Wikimedia Commons)

It was the best of times. In the nineteenth century England, the Industrial Revolution started a time of important social and political change. London became the financial capital of the world. Several scientific societies were forming, such as the Geological Society of London, while fascinating discoveries revealed part of the history of our planet. But it was also the worst of time. England was ruled by an elite, meanwhile most of the people were poor. Churches provided schools for poor children and infant mortality was high. During these difficult times, Charles Dickens revitalized the tradition of Christmas and to Victorian England, Dickens was Christmas.  He had only 31, when began to write A Christmas Carol. The novella tells the story of  Ebenezer Scrooge, a bitter old man who finds salvation through the visits of the three Ghosts of Christmas (Ghost of Christmas Past, Ghost of Christmas Present, and Ghost of Christmas Yet to Come).

Charles Dickens also contributed to the popularity of geology in the nineteenth century. For him, the ideal science was Geology. In his review of Hunt’s Poetry of Science, he wrote: “Science has gone down into the mines and coal-pits, and before the safety-lamp the Gnomes and Genii of those dark regions have disappeared … Sirens, mermaids, shining cities glittering at the bottom of quiet seas and in deep lakes, exist no longer; but in their place, Science, their destroyer, shows us whole coasts of coral reef constructed by the labours of minute creatures; points to our own chalk cliffs and limestone rocks as made of the dust of myriads of generations of infinitesimal beings that have passed away; reduces the very element of water into its constituent airs, and re-creates it at her pleasure…” (London Examiner, 1848).

Hawkins’ Sydenham Studio. From Wikimedia Commons.

When the Crystal Palace was opening at Sydenham, Dickens addressed the sculptor Benjamin Waterhouse Hawkings to ensure that the dinosaurs he had named, including the megalosaurus, and the iguanodon, were accurately recreated. In Bleak House and Dombey and Son, Dickens encourage readers to perceive the scene of the city as a geological fragment of a much broader spatial and temporal vision. In Bleak House the dinosaurs uncovered by the railway in Dombey and Son move centre stage: “Implacable November weather. As much mud in the streets as if the waters had but newly retired from the face of the earth, and it would not be wonderful to meet a Megalosaurus, forty feet long or so, waddling like an elephantine lizard up Holborn Hill.” 

Among his friends were Richard Owen and Sir Roderick Murchison. Murchinson’s wife, Charlotte, was a very close friend of Mary Anning, the most famous fossilist of the time. Mary has been called “the Princess of Palaeontology”  by the German explorer Ludwig Leichhardt and scientists like William Buckland or Henry de la Beche owe their achievements to Mary’s work. She discovered (along with her brother Joseph) the first specimens of what would later be recognized as Ichthyosaurus, the first complete Plesiosaurus, the first pterosaur skeleton outside Germany, and a fossil fish, with characteristics intermediate between sharks and rays, called Squaloraja (unfortunately, the specimen was lost in the destruction of the Bristol Museum by a German bombing raid in November, 1940)

Skull of an ichthyosaur painted with fossil sepia by Elizabeth Philpot.

Mary Anning was born on Lyme Regis on May 21, 1799. Her father was a carpenter and an amateur fossil collector who died when Mary was eleven. By the age of 27, Mary was the owner of a little shop: Anning’s Fossil Depot. Many scientist and fossil collectors from around the globe went to Mary´s shop. She was friend of Henry De la Beche, the first director of the Geological Survey of Great Britain, who knew Mary since they were both children and lived in Lyme Regis. De la Beche was a great supporter of Mary’s work. She also corresponded with Charles Lyell, William Buckland and Mary Morland, Adam Sedgwick and Sir Roderick Murchison. It’s fairly to say that Mary felt secure in the world of men, and a despite her religious beliefs, she was an early feminist. In an essay in her notebook, titled Woman!, Mary writes: “And what is a woman? Was she not made of the same flesh and blood as lordly Man? Yes, and was destined doubtless, to become his friend, his helpmate on his pilgrimage but surely not his slave…”

The article published in All the Year Round in 1865, about the life of Mary Anning. From the Internet Archive

In 1865, Charles Dickens wrote an article about Mary Anning’s life in his literary magazine “All the Year Round”, where emphasised the difficulties she had overcome: “Miss Anning wrote sadly enough to a young girl in London: “I beg your pardon for distrusting your friendship. The world has used me so unkindly, I fear it has made me suspicious of every one.” 

Mary Anning, ‘the greatest fossilist the world ever knew’, died of breast cancer on 9 March, 1847, at the age of 47. She was buried in the cemetery of St. Michaels. In the last decade of her life, Mary received three accolades. The first was an annuity of £25, in return for her many contributions to the science of geology. The second was in 1846, when the geologists of the Geological Society of London organized a further subscription for her. The third accolade was her election, in July 1846, as the first Honorary Member of the new Dorset County Museum in Dorchester. About her life and legacy Dickens wrote: “Her history shows what humble people may do, if they have just purpose and courage enough, toward promoting the cause of science. The inscription under her memorial window commemorates “her usefulness in furthering the science of geology” (it was not a science when she began to discover, and so helped to make it one), “and also her benevolence of heart and integrity of life.” The carpenter’s daughter has won a name for herself, and has deserved to win it.” 

References:

Dickens, Charles, 1812-1870, `Mary Anning, the Fossil-Finder’, All the year round, Volume XIII, Magazine No. 303, 11 February 1865, Pages: 60-63

A. BUCKLAND, ‘“The Poetry of Science”: Charles Dickens, Geology and Visual and Material Culture in Victorian London’, Victorian Literature and Culture, 35 (2007), 679–94 (p. 680).

A. BUCKLAND. Novel Science: Fiction and the Invention of Nineteenth-Century Geology. Chicago, IL and London: University of Chicago Press, 2013. 400 pp. 9 plts. $45.00. ISBN 978-0-226-07968-4

 

Introducing Asfaltovenator vialidadi

Skeletal reconstruction and postcranial anatomy of Asfaltovenator vialidadi, MPEF PV 3440. From Rauhut and Pol, 2019.

During the Jurassic (201-145 mya) the breakup of the supercontinent Pangaea continued and accelerated with the opening of the North Atlantic by the rifting of Africa and North America, giving rise to the supercontinents of Laurasia and Gondwana. The sea level rise flooded continental areas around Pangaea, forming huge epicontinental seas, especially in northern Africa and eastern Laurasia (modern China). The world was predominantly warm with at least four times the present level of atmospheric CO2. The period is also characterized by the explosive adaptive radiation of dinosaurs.

By the Mid-Jurassic, Gondwana, the southern margen of supercontinent Pangea started to break up in different blocks: Antarctica, Madagascar, India, and Australia in the east, and Africa and South America in the west. During this period, the Tetanurae reached a global distribution. Tetanuran theropods comprise the majority of Mesozoic predatory dinosaurs, including Allosaurus and Tyrannosaurus, and the lineage leading to extant birds. Unfortunatelly, the fragmentary nature of the earliest known members of this group difficults our understanding of their early radiation. Asfaltovenator vialidadi gen. et sp. nov., a new basal tetanuran from the Middle Jurassic of Argentina, shed new ligth on the early radiation of this group. The generic name refers from Cañadón Asfalto Formation, the site where the fossil was found, and venator, a Greek word for hunter. The specific name honors the Administración de Vialidad Provincial of Chubut and the Dirección Nacional de Vialidad, for their aid to the Museo Paleontológico Egidio Feruglio.

Cranial anatomy of Asfaltovenator vialidadi. From Rauhut and Pol, 2019.

Discovered in 2002 by Leandro Canesa, the holotype (MPEF PV 3440) includes an almost complete skull and a partial skeleton. The skull is high and slightly arched, similar to that of other allosauroids and reached 75–80 cm long. The estimated body length of the holotype is 7–8 m, which makes Asfaltovenator comparable in size to the well-known Allosaurus.

Asfaltovenator shows an unusual mosaic of tetanuran characters. Megalosauroid characters include a pronounced kink in the anterodorsal margin of the maxillary ascending process, a medially closed maxillary fenestra, a deep posterior groove on ventral process of postorbital, and a broad fossa below the occipital condyle. Allosauroid characters include the presence of a pronounced supranarial fossa, the nasal participation in the antorbital fossa, presence of pneumatic foramina in the nasal, and lateral nasal crests.

llustration of the Asfaltovenator (Credit: Gabriel Lio/Conicet)

Tetanurae has been tradionally divided in three major clades: Megalosauroidea, Coelurosauria, and Allosauroidea. The phylogenetic analysis of A. vialidadi suggest that Allosauroidea  and Megalosauroidea have a common ancestor that they do not share with coelurosaurs. The new study also suggest that the Pliensbachian-Toarcian extinction event was a potential driver of tetanuran radiation.

References:

Rauhut, Oliver W. M.; Pol, Diego (2019), Probable basal allosauroid from the early Middle Jurassic Cañadón Asfalto Formation of Argentina highlights phylogenetic uncertainty in tetanuran theropod dinosaurs https://www.nature.com/articles/s41598-019-53672-7

Carrano, M. T., Benson, R. B. J., & Sampson, S. D. (2012). The phylogeny of Tetanurae (Dinosauria: Theropoda). Journal of Systematic Palaeontology, 10(2), 211–300. doi:10.1080/14772019.2011.630927