Gnathovorax cabreirai and the origin of predatory dinosaurs

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

Herrerasauridae is a basal clade of predatory, obligatorily bipedal dinosaurs recorded from the Upper Triassic of Argentina and Brazil (although are putative records of herrerasaurids from the mid-late Norian strata of Europe and North America). The clade unequivocally comprises three species: Herrerasaurus ischigualastensis, Sanjuansaurus gordilloi, both from the Ischigualasto Formation of Argentina, and Staurikosaurus pricei, from the lower portion of the Santa Maria Formation of southern Brazil. Now, a new specimen from the Santa Maria Formation shed light into poorly understood aspects of the Herrerasauridae anatomy.

Named Gnathovorax cabreirai, the new dinosaur 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.

Photographs and reconstruction of the braincase and endocast of Gnathovorax cabreirai. From Pacheco et al., 2019.

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.

The study of the internal anatomy of the skull through CT-scanning reveals several aspects of the neuroanatomy of this group. The presence of a well-developed floccular fossa lobes of the cerebellum is related to motor control of the eye and head, which in turn may be related to the predatory habit of the group.

References:
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

Meet Ferrisaurus sustutensis, the iron lizard from the Sustut River.

 

Preserved elements of the holotype of Ferrisaurus sustutensis. From Arbour and Evans, 2019.

In 1971, during uranium and thorium exploration in the Sustut Basin of northern British Columbia, Canada, Kenny F. Larsen registered above-background levels of radiation from a talus slope near the confluence of Birdflat Creek and the Sustut River. The source of this radiation were the fossil remains of an unknow dinosaur. Larsen, an economic geologist, donated the bones to the Dalhousie University (Halifax, NS) in 2004. Later, the specimen was accessioned into the collection of the Royal British Columbia Museum in Victoria, BC.

Initially described as a pachycephalosaur or a basal ornithopod similar to Thescelosaurus, a new study determined that the remains belongs to a new genus and species: Ferrisaurus sustutensis. The holotype (RBCM P900) includes portions of the pectoral girdles, left forelimb, left hindlimb, and right pes. The name derived from Latin ferrum (=iron) and Greek sauros (=lizard), referencing to the specimen’s discovery along a railway line. The specific name honors its provenance near the Sustut River and within the Sustut Basin.

Pedal elements of Ferrisaurus sustutensis compared to other Laramidian small-bodied ornithischians. From Arbour and Evans, 2019.

Despite the lack of cranial material Ferrisaurus can be placed within leptoceratopsids based on several aspects of the preserved phalanges. Leptoceratopsids were short-frilled, hornless ceratopsians that lived in Campanian–Maastrictian aged dinosaur assemblages from Asia and North America. Ferrisaurus measured about 1.75 metres in length and 150 kilograms in weight and is similar in size to large specimens of Leptoceratops and Cerasinops.

 

References:

Arbour VM, Evans DC. 2019. A new leptoceratopsid dinosaur from Maastrichtian-aged deposits of the Sustut Basin, northern British Columbia, Canada. PeerJ 7:e7926 https://doi.org/10.7717/peerj.7926

Arbour, V. M., & Graves, M. C. (2008). An ornithischian dinosaur from the Sustut Basin, north-central British Columbia, Canada. Canadian Journal of Earth Sciences, 45(4), 457–463. doi:10.1139/e08-009 

Halloween special VII: A story of Darkness and Climate Change.

In April of 1815 the eruption of Mount Tambora released two million tons of debris and sulphur components into the atmosphere. The following year was known as “the year without summer”. The eruption produced famine, riots, and disease outbreak. Charles Lyell describes the eruption in his Principles of Geology: “Great tracts of land were covered by lava, several streams of which, issuing from the crater of the Tomboro Mountain, reached the sea. So heavy was the fall of ashes, that they broke into the Resident’s house at Bima, forty miles east of the volcano, and rendered it, as well as many other dwellings… The darkness occasioned in the daytime by the ashes in Java was so profound, that nothing equal to it was ever witnessed in the darkest night.”

The 1815 eruption of Tambora volcano (Sumbawa island, Indonesia) was the largest volcanic eruption in the last 500 years. The dust, gas, rock and pyroclastic flows hitted the surronding sea hard enough to set off moderate-sized tsunami that struck the shores of various islands in the Indonesian archipelago. Over 71 000 people died during, or in the aftermath of, the eruption near Sumbawa and the island of Lombok. The nothern hemisphere experienced severe weather. Summer temperatures across much of western and central Europe were 1–2°C cooler than the average for the period 1810–1819.

The Villa Diodati. Image from Finden’s Landscape & Portrait Illustrations to the Life and Works of Lord Byron, vol. 2 (London: John Murray, 1832).

The event inspired the great romantic poet Lord Byron to wrote “Darkness”:

I had a dream, which was not all a dream.
The bright sun was extinguish’d, and the stars
Did wander darkling in the eternal space,
Rayless, and pathless, and the icy earth
Swung blind and blackening in the moonless air;
Morn came and went—and came, and brought no day,
And men forgot their passions in the dread…”
The poem, with a vision of an icy Earth full of desolation and despair was published in 1816. At the time, after a failed marriage, scandalous affairs and huge debts, Byron left England and never returned. He traveled to Switzerland whith his physician, Dr John William Polidori, where he met up with Percy Bysshe Shelley and Mary Wollstonecraft Godwin (she married Shelley later that year) at the Villa Diodati on the banks of Lake Geneva. The meeting was organized by Clare Clairmont, Mary’s step-sister and a former lover of Lord Byron, because Shelley wanted to meet the great poet.
Years later, Mary Shelley wrote about their stay at Geneva: “it proved a wet, ungenial summer, and incessant rain often confined us for days to the house. Some volumes of ghost stories translated from the German into French, fell into our hands. There was the History of the Inconstant Lover, who, when he thought to clasp the bride to whom he had pledged his vows, found himself in the arms of the pale ghost of her whom he had deserted. There was the tale of the sinful founder of his race, whose miserable doom it was to bestow the kiss of death on all the younger sons of his fated house, just when they reached the age of promise.” 

Illustration from the frontispiece of the 1831 edition of Frankestein.

Byron proposed a ghost story contest. They all agreed. Byron wrote a short, fragmentary vampire tale. Shelley wrote a tale inspired by his childhood. Polidori used Byron’s tale and wrote The Vampyre. The story was first published in April 1819 in Henry Colburn’s New Monthly Magazine. Byron himself was the model for the vampire character, Lord Ruthven. The story was an immediate popular success and influenced Bram Stoker’s Dracula.
Mary’s contribution was Frankenstein: “I busied myself to think of a story, —a story to rival those which had excited us to this task. One which would speak to the mysterious fears of our nature, and awaken thrilling horror—one to make the reader dread to look round, to curdle the blood, and quicken the beatings of the heart.”
As in “Darkness”, Frankenstein deal with desolation and despair. Both are notable examples of the narrative of the climate disaster and the trauma unfolding around them in the Tambora years of 1816-18.
Mount Tambora continued rumbling intermittently at least up to August 1819. Once it was similar in stature to Mont Blanc. And of course, Mer de Glace, on the slope of the mountain, is where Victor Frankenstein reunited with his Creature: “From the side where I now stood Montenvers was exactly opposite, at the distance of a league; and above it rose Mont Blanc, in awful majesty…. The sea, or rather the vast river of ice, wound among its dependant mountains, whose aerial summits hung over its recess….” (Mary Shelley, Frankenstein, 1818)
References:
Oppenheimer, C. (2003). Climatic, environmental and human consequences of the largest known historic eruption: Tambora volcano (Indonesia) 1815. Progress in Physical Geography, 27(2), 230–259. doi:10.1191/0309133303pp379ra
Shelley, Mary. (1818) Frankenstein or, The Modern Prometheus. [via Gutenberg Project.]
Polidori, John. (1819) The Vampyre and Other Tales of the Macabre. [via Gutenberg Project.]

Mutagenesis in land plants during the end-Triassic mass extinction

 

A basaltic lava flow section from the Middle Atlas, Morocco. From Wikimedia Commons.

During the last 540 million years five mass extinction events shaped the history of the Earth. The End-Triassic Extinction at 201.51 million years (Ma) is probably the least understood of these events. Most mammal-like reptiles and large amphibians disappeared, as well as early dinosaur groups. In the oceans, this event eliminated conodonts and nearly annihilated corals, ammonites, brachiopods and bivalves. In the Southern Hemisphere, the vegetation turnover consisted in the replacement to Alisporites (corystosperm)-dominated assemblage to a Classopollis (cheirolepidiacean)-dominated one.

The mass extinction event was likely caused by the eruption of the Central Atlantic Magmatic Province (CAMP), a large igneous province emplaced during the initial rifting of Pangea. Data indicates that magmatic activity started c. 100,000 years before the endTriassic event and continued in pulses for 700,000 years. The CO2 emissions caused global warming. The SO2 emissions on mixing with water vapour in the atmosphere, caused acid rain, which in turn killed land plants and caused soil erosion.

A normal fern spore compared with mutated ones from the end-Triassic mass extinction event. Image credit: S LINDSTRÖM, GEUS

Volcanoes are also a primary source of mercury (Hg) in the global atmosphere. Mercury can cause morphologically visible abnormalities in plants and their reproductive cells (spores and pollen). A new study led by Sofie Lindström of the Geological Survey of Denmark and Greenland analized various types of abnormalities in the reproductive cells of ferns, with focus in two morphogroups: LTT-spores (laevigate, trilete fern spores with thick exine), and LCT-spores (laevigate, circular, trilete spores). The LTT-spores were produced primarily by the fern families Dipteridaceae, Dicksoniaceae, and Matoniaceae, while LCT spores were primarily produced by ferns belonging to Osmundaceae and Marattiales.

The elevated concentrations of mercury (Hg) in sedimentary rocks in North America, Greenland, England, Austria, Morocco, and Peru are linked to CAMP eruptions. This pulse of mercury also correlate with high occurrences of abnormal fern spores, indicating severe environmental stress and genetic disturbance in the parent plants. Three negative organic C-isotope excursions (CIEs) have being recognized at the end-Triassic: the Marshi, the Spelae, and the top-Tilmanni CIEs. Malformations in LTT-spores first occur sporadically in the lower pre-Marshi interval. LCT-spores are present but are generally rare in this interval. During the Spelae CIE, the occurrences of moderate to severe malformations increased and aberrant forms can encompass as much as 56% of the counted LTT-spores. This interval is associated with marked global warming, recorded by stomatal proxy data.

 

 

References:

Sofie Lindström et al. Volcanic mercury and mutagenesis in land plants during the end-Triassic mass extinction, Science Advances (2019). DOI: 10.1126/sciadv.aaw4018}

Grasby, S. E., Them, T. R., Chen, Z., Yin, R., & Ardakani, O. H. (2019). Mercury as a proxy for volcanic emissions in the geologic record. Earth-Science Reviews, 102880. doi:10.1016/j.earscirev.2019.102880

Ocean acidification and the end-Cretaceous mass extinction

Heterohelix globulosa foraminifera isolated from the K-Pg boundary clay at Geulhemmerberg in the Netherlands. Image credit: Michael J. Henehan/PNAS

The Cretaceous–Paleogene extinction that followed the Chicxulub impact was one of the five great Phanerozoic mass extinctions. Three-quarters of the plant and animal species on Earth disappeared, including non-avian dinosaurs, pterosaurs, marine reptiles, ammonites, and planktonic foraminifera. 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 impacto also caused sudden ocean acidification, impacting marine ecosystems and the carbon cycle. Around the time of the impact, 23,000 to 230,000 cubic miles of magma erupted out of the mid-ocean ridges, all over the globe. One of the largest eruptive events in Earth’s history. This pulse of global marine volcanism played an important role in the environmental crisis at the end of the Cretaceous. Marine volcanism also provides a potential source of oceanic acidification, but a new 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.

Foraminifera are crucial elements for our understanding of past and present oceans. Their skeletons 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. Ocean acidification in the geological record is often inferred from a decrease in the accumulation and preservation of CaCO3 in marine sediments, potentially indicated by an increased degree of fragmentation of foraminiferal shells. In the early 1990’s it was recognised that the boron isotopic composition of marine carbonates was determined largely by ocean pH. Usingy the boron isotope-pH proxy to planktic and benthic foraminifera, the new study determinated the ocean pH drop following the Chicxulub impact.

The Cretaceous/Palaeogene extinction boundary clay at Geulhemmerberg Cave. Image credit: Michael J. Henehan

The boron isotope composition of carbonate samples obtained from a shallow-marine sample site (Geulhemmerberg Cave, The Netherlands) preserved sediments from the first 100 to 1000 years after the asteroid’s impact. The data from the Geulhemmerberg Cave indicate a marked ∼0.25 pH unit surface ocean acidification event within a thousand years. This change in pH corresponds to a rise in atmospheric partial pressure of CO2 (pCO2) from ∼900 ppm in the latest Maastrichtian to ∼1,600 ppm in the immediate aftermath of bolide 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.

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. 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. This underlines the urgency for immediate action on global carbon emission reductions.

 

 

References:

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

Kump, L.R., T.J. Bralower, and A. Ridgwell. 2009. Ocean acidification in deep time. Oceanography 22(4):94–107, https://doi.org/10.5670/oceanog.2009.100.

 

The Last Mammoths

Mammuthus primigenius, Royal British Columbia Museum. From Wikipedia Commons

During the Late Pleistocene and early Holocene, most of the terrestrial megafauna became extinct. It was a deep global-scale event. The extinction was notably more selective for large-bodied animals than any other extinction interval in the last 65 million years. Among them, the mammoths offers a very complete fossil record, and their evolution is usually presented as a succession of chronologically overlapping species, including (from earliest to latest) M. meridionalis (southern mammoths), M. trogontherii (steppe mammoths), and M. columbi (Columbian mammoths) and M. primigenius (woolly mammoths).

Wrangel Island coast. From Wikipedia Commons

From Siberia to Alaska, mammoths were widespread in the northern hemisphere and their remains inspired all types of legends. Their lineage arose in Africa during the late Miocene, and first appeared in Europe almost three million years ago. The iconic M. primigenius arose in northeastn Siberia from the steppe mammoth (Mammuthus trogontherii) and their extinction has inspired an impressive body of literature. Multiple explanatory hypotheses have been proposed for this event: climatic change, overhunting, habitat alteration, and the introduction of a new disease.

The world’s last population of woolly mammoths lived on Wrangel Island going extinct around 4,000 years ago. In contrast the mammoth population from Russia disappeared about 15,000 years ago, while the mammoths of St. Paul Island in Alaska disappeared 5,600 years ago. The Wrangel Island was a part of Beringia, an ancient landmass, that included the land bridge between Siberia and Alaska. Global sea level transgression at the end of the Pleistocene isolated Wrangel Island from the mainland and broke up Beringia. Palynological and isotopic evidence suggest that present climatic conditions and floral composition were established right after the Pleistocene-Holocene transition.

A mammoth tooth on the riverbank on Wrangel Island. Image credit; Juha Karhu/University of Helsinki

Tooth specimens are about 90% of all the mammoth material for Wrangel Island. The multi-isotopic evidence (carbon, nitrogen and sulfur in collagen) measured on Wrangel Island mammoths supports the idea that this relict population mantained a typical mammoth ecology despite climate change and decreasing genetic diversity. It has been suggested that the extinction of the Wrangel Island mammoths was possibly caused by a short-term crisis, possibly linked to climatic anomalies, however the anthropogenic influence should not be dismissed despite lack of tangible evidence of hunting.

 

References:

Laura Arppe, Juha A. Karhu, Sergey Vartanyan, Dorothée G. Drucker, Heli Etu-Sihvola, Hervé Bocherens. Thriving or surviving? The isotopic record of the Wrangel Island woolly mammoth population. Quaternary Science Reviews, 2019; 222: 105884 DOI: 10.1016/j.quascirev.2019.105884

Meet Ferrodraco lentoni, the Iron Dragon

Ferrodraco lentoni gen. et sp. nov. holotype. Scale bar = 50 mm. From Pentland et al., Scientific Reports.

Pterosaurs were the first flying vertebrates. From the Late Triassic to the end of the Cretaceous, the evolution of pterosaurs resulted in a variety of eco-morphological adaptations, as evidenced by differences in skull shape, dentition, neck length, tail length and wing span. Their reign extended to every continent, but due to the fragile nature of their skeletons the fossil record of pterosaurs is rather patchy, with most occurrences limited to fragmentary remains. The newly described Ferrodraco lentoni, from the Winton Formation (Cenomanian–lower Turonian), is the most complete pterosaur specimen ever found in Australia. Previously, and only based on fossil skull fragments, two other species of pterosaurs were described from Australia: Mythunga camara and Aussiedraco molnari.

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.

Ferrodraco lentoni gen. et sp. nov. holotype rostral sections AODF 876. Cross-section. Scale bar = 20 mm. From Pentland et al., Scientific Reports.

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. It has been suggested that anhanguerians went extinct at the end of the Cenomanian. This interval was characterised by an increase in atmospheric and oceanic surface temperatures, a global oceanic anoxic event, and marine transgression. Given that Ferrodraco was recovered from a locality northeast of Winton, which is considered as early Turonian in age, the new specimen potentially represents a late-surviving member of the anhanguerians.

 

References:

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

Aftermath: The first day of the Cenozoic

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

In the late ’70, 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. In 1981, 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, making the feature one of the largest confirmed impact structures on Earth. The Cretaceous–Paleogene extinction that followed the Chicxulub impact was one of the five great Phanerozoic mass extinctions. 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 Chicxulub impact site is the only known impact structure on Earth with an unequivocal peak ring but it is buried and only accessible through drilling. In April to May 2016, a team by International Ocean Discovery Program (IODP) and International Continental Scientific Drilling Program (ICDP) drilled the Chicxulub peak ring offshore. The core recovered during the expedition provides a window into the immediate aftermath of the impact.

Timeline of events recorded inside the impact crater.

The recovered core was divided into 4 Units. The Unit 1 is 111.63-m-thick postimpact sedimentary rock. The Unit 2 is 104.28-m thick and dominantly suevite. The Unit 3 is 25.41-m-thick impact melt rock, with some clasts present. The Unit 4 consists of shocked granitic target rocks, preimpact sheet intrusions, and intercalations of suevite and impact melt rock. There are high abundances of charcoal in Unit 1. The charcoal likely originated from impact-related combustion of forested landscapes surrounding the Gulf of Mexico. Data indicate that Chicxulub impact released sufficient thermal radiation to ignite flora up to 1,000 to 1,500 km from the impact site. The upper few centimeters of the unit 2 contain abundant reworked Maastrichtian planktic foraminifera that indicate redeposition of sediments that were unconsolidated at the time of the impact.

The lack of evaporites in the recovered sedimentary section, supports the impact generated sulfate aerosol production and extinction mechanisms, including global cooling and limitations on photosynthesis. Core samples also revealed that a high-temperature hydrothermal system was established within the crater but the appearance of burrowing organisms within years of the impact indicates that the hydrothermal system did not adversely affect seafloor life. These impact-generated hydrothermal systems are hypothesized to be potential habitats for early life on Earth and other planets.

 

References:

Sean P. S. Gulick, Timothy J. Bralower, Jens Ormö, Brendon Hall, Kliti Grice, Bettina Schaefer, Shelby Lyons, Katherine H. Freeman, Joanna V. Morgan, Natalia Artemieva, Pim Kaskes, Sietze J. de Graaff, Michael T. Whalen, Gareth S. Collins, Sonia M. Tikoo, Christina Verhagen, Gail L. Christeson, Philippe Claeys, Marco J. L. Coolen, Steven Goderis, Kazuhisa Goto, Richard A. F. Grieve, Naoma McCall, Gordon R. Osinski, Auriol S. P. Rae, Ulrich Riller, Jan Smit, Vivi Vajda, Axel Wittmann, and the Expedition 364 Scientists. The first day of the Cenozoic. PNAS, 2019 DOI: 10.1073/pnas.1909479116

Morgan, J. V., Gulick, S. P. S., Bralower, T., Chenot, E., Christeson, G., Claeys, P., … Zylberman, W. (2016). The formation of peak rings in large impact craters. Science, 354(6314), 878–882. doi:10.1126/science.aah6561

Christopher M. Lowery et al. Rapid recovery of life at ground zero of the end-Cretaceous mass extinction, Nature (2018). DOI: 10.1038/s41586-018-0163-6

A new dinosauriform specimen from the Chañares Formation of north-western Argentina.

 

(A) preserved bones of CRILAR-Pv 552 in approximate anatomical arrangement. (B) skeletal reconstruction of Lewisuchus admixtus. From Ezcurra et. al, 2019.

Formed during the breakup of Gondwana, the Chañares Formation is part of the Ischigualasto-Villa Unión Basin, and represents one of the most continuous continental Triassic succesions in South America. Volcanism have played an important role in the generation and preservation of the Chañares Formation’s exceptional tetrapod fossil record. The diverse and well-preserved tetrapod assemblage includes proterochampsids, pseudosuchians, ornithodirans, large dicynodonts and smaller cynodonts. Almost all dinosauromorphs are preserved in diagenetic concretions that erode out of a thick siltstone interval 15–20 m above the base of the formation, and include Lagosuchus talampayensis, Marasuchus lilloensis, Lewisuchus admixtus, and Pseudolagosuchus major. 

Unfortunatelly, our knowledge about Lewisuchus admixtus, and Pseudolagosuchus major are based on partial skeletons that has generated a contentious debate during the last 20 years about the synonymy between two of these species. The discovery of a new dinosauriform partial skeleton (CRILAR‐Pv 552) allows comparisons for the first time with both Lewisuchus admixtus and Pseudolagosuchus major.

Geological map of the Chañares–Gualo area in Talampaya National Park (From Marsicano et al., 2015)

The new specimen was found in 2013, and includes fragments of both premaxillae and maxillae, partial right jugal, right quadrate, fragment of right pterygoid, supraoccipital, both prootics, parabasisphenoid, right dentary lacking posterior end, anterior end of left dentary, partial right retroarticular complex, an isolated tooth, three or four anteriormiddle cervical vertebrae, distal half of a posterior cervical or dorsal neural spine, two middleposterior dorsal vertebrae, two sacral vertebrae, two consecutive anterior caudal vertebrae, eight to ten middle-distal caudal vertebrae, two haemal arches, base of the left scapular blade, partial left coracoid, distal half of right humerus, proximal region and distal end of left ulna, distal end of left radius, proximal region of a metacarpal, partial ilia, proximal end of left pubis, distal end of both pubes, partial left ischium, both partial femora, almost complete left tibia, distal end of right tibia, partial left half of fibula, partial fibular shaft, and some possible metatarsal shaft fragments. Based on the unique combination of cranial and postcranial characters, CRILAR-Pv 552 can be referred to Lewisuchus admixtus, and supports the hypothesis that Pseudolagosuchus major is a subjective junior synonym of Lewisuchus admixtus.

 

References:

Ezcurra, M. D., Nesbitt, S. J., Fiorelli, L. E., & Desojo, J. B. (2019). New specimen sheds light on the anatomy and taxonomy of the early Late Triassic dinosauriforms from the Chañares Formation, NW Argentina. The Anatomical Record. doi:10.1002/ar.24243

Marsicano, C. A.Irmis, R. B.Mancuso, A. C.Mundil, R. & Chemale, F., The precise temporal calibration of dinosaur origins, Proc. Natl Acad. Sci. USAhttp://dx.doi.org/10.1073/pnas.1512541112 (2015).

The Great Female Scientists of the Victorian Era

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

Women have played  various and extensive roles in the history of geology. Unfortunately, their contribution has not been widely recognised by the public and the history of geosciences has largely been interpreted as a history of male scientists.

In the Victorian times there was the common assumption that the female brain was too fragile to cope with mathematics, or science in general. In a letter from March 1860, Thomas Henry Huxley wrote to Charles Lyell: “Five-sixths of women will stop in the doll stage of evolution, to be the stronghold of parsonism, the drag on civilisation, the degradation of every important pursuit in which they mix themselves – intrigues in politics and friponnes in science.” Lyell, one of the most famous geologist of his time, was married to Mary Horner, daughter of the geologist Leonard Horner, and one of the many female contributors to geology in the early nineteenth century in the United Kingdom. A list that also includes Mary Anning, Barbara Hastings, Etheldred Bennet, the Philpot sisters, Mary Buckland née Morland, Charlotte Murchinson, Elizabeth Cobbold, Mary Buckland née Morland, Charlotte Murchinson, Mary Sommerville, Jane Marcet, Delvalle Lowry, and Arabella Buckley. Those women formed a framework of assistants, secretaries, collectors, field geologists, illustrators, and as popularizers of science.

Duria Antiquior famous watercolor by the geologist Henry de la Beche based on fossils found by Mary Anning. From Wikimedia Commons.

The nineteen century was the “golden age” of Geology. The Industrial Revolution ushered a period of canal digging and major quarrying operations for building stone. These activities exposed sedimentary strata and fossils. The concept of an ancient Earth became part of the public understanding and Literature influenced the pervasiveness of geological thinking. The most popular aspect of geology was the collecting of fossils and minerals and the nineteenth-century geology, often perceived as the sport of gentlemen,was in fact, “reliant on all classes”. Due to the informal character of the early British geology, women were free to take part in collecting fossils and mineral specimens, and they were allowed to attend lectures, but they were still barred from membership in scientific societies. Women interested in geology could attend the meetings of the British Association for the Advancement of Science (BAAS). Also, the public lectures at the Royal Institution were very popular among educated women. About the BAAS meeting at York (1831), Charles Lyell wrote: “A hundred and fifty ladies, and many of rank, at the evening discussion, must also have ‘popularised’ scientific pursuits”.

William Whewell, contrary to some other colleagues, welcomed scientific women to the third meeting of the British Association in 1834. In an invitation addressed to Mary Somerville, he wrote: “I expect Mrs. Buckland and Mrs. Murchinson and several other ladies…”

Autograph letter about the discovery of plesiosaurus, by Mary Anning. From original manuscripts held at the Natural History Museum, London. © The Natural History Museum, London

Early female scientists were often born into influential families, like Grace Milne, the eldest child of Louis Falconer and sister of the eminent botanist and palaeontologist, Hugh Falconer; or Mary Lyell, the daughter of the geologist Leonard Horner. Althought Barbara Hastings (1810-1858) and Etheldred Benett (1776–1845) published their works independently, the prevailing pattern was formed by women who have worked in the field but acted as assistants to father, husband, brother, or other male geologist that were no relatives. In these cases, the publication of their findings was not part of accepted females activy, and their contribution is often completely concealed under the name of someone else. Even Lyell wrote about the iniquity of the situation in a letter to his future wife, Mary Horner: “Had our friend Mrs. Somerville been married to La Place, or some mathematician, we should never have hear of her work. She would have merged it in her husband’s, and passed it off as his.” 

Although she was not formally published, Etheldred Benett wrote several manuscripts, which are now in the collections of the Geological Society of London. She was a lady, a member of the landed gentry, and unlike Mary Anning, Etheldred Bennet was in a very confortable financial circumstances. She described the stratigraphic and geographic distribution of fossils of Wiltshire, and for more than 30 years she was frequently acknowledged in the publications of palaeontologist and geologist throughout Europe.

Portrait of Barbara Rawdon Hastings (née Yelverton), Marchioness of Hastings. From Wikimedia Commons

Barbara Rawdon (née Yelverton) Hastings (1810–1858), 20th Baroness Grey de Ruthyn and Marchioness of Hastings was known as a fossil collector and a “lady-geologist” . She is also well known for the “Hastings Collection,” consisting of several thousand fossil specimens from England and Europe. She also studied the stratigraphy of England and published her findings in “Description géologique des falaises d’Hordle, et sur la côte de Hampshire, en Angleterre” (Hastings, 1851–52) and “On the tertiary beds of Hordwell, Hampshire” (Hastings, 1853).

The Philpot sisters (Margaret, ?–1845; Mary, 1773?–1838; Elizabeth, 1780–1857) were also well know for their fossil collection and their friendship with Mary Anning. They came from educated, middle-class London, and after their parents dead, they moved to Lymes Regis and amassed an important collection of fossils. Elizabeth maintained correspondences with William Buckland, William Conybeare, Henry De la Beche, Richard Owen, James Sowery and Louis Agassiz. About Elizabeth, Agassiz wrote: “I have the pleasure to recognize publicly the service, that she rendered to palaeontology and specially to fossil ichtyology, in collecting with much ardour the fossil relicts in the Lias of Lyme Regis.”

Mary Horner Lyell (1808-1873) British geologist. Daughter of geologist Professor Leonard Horner, wife of Sir Charles Lyell.

In the other group we could find those women who worked with their husbands. The most prominent of these women were Mary (née Moreland) Buckland (1797–1857), wife of Rev. William Buckland; Mary Ann (née Woodhouse) Mantell (1795–1869), wife of Dr. Gideon Mantell; Charlotte (née Hugonin) Murchison (1789–1869) wife of Sir Roderick Murchison; and Mary Elizabeth (née Horner) Lyell (1808–1873), wife of Sir Charles Lyell (Davis, 2009).

Mary Morland (1797–1857) illustrated some of George Cuvier’s work before she became Mrs William Buckland. She made models of fossils for the Oxford museum and repaired broken fossils. She assisted her husband by taking notes of his observations and illustrating his work. After the death of her husband, she continued working on marine zoophytes.

Charlotte Murchinson (1789–1869) was a strong influence for her husband and introduced him in the world of geology. She accompanied him on excursions and spent time sketching the  landscape and outcrops and collecting Jurassic fossil specimens from the beaches.

Mary Mantell and the lithographed of an Iguanodon teeth.

Mary Mantell (1795–1869) discovered the teeth of Iguanodon, which led to her husband’s publication of an important paper announcing the discovery of a new giant reptile (Creese and Creese, 1994). She also made the illustration of Mantell’s work: “Fossils of the South Downs: or Illustrations of the Geology of Sussex”. Mary Mantell left her husband in 1839 and the children remained with their father as was customary.

Mary Lyell (1808–1873) was daughter of the geologist Leonard Horner. She read both French and German fluently and translated scientific papers for her husband and managed his correspondence. She later specialized in conchology and regularly attended meetings of the London Geological Society.

 

Sketch of Mary Anning by Henry De la Beche.

Mary Anning (1799-1847), was an special case. Despite her lower social condition and the fact that she was single, Mary became the most famous woman paleontologist of her time. She found the first specimens of what would later be recognized as Ichthyosaurus, the first complete Plesiosaurus, the first pterosaur skeleton outside Germany and suggested that the “Bezoar stones” were fossilized feces. After her death, Henry de la Beche, Director of the Geological Survey and President of the Geological Society of London, wrote a very affectionate obituary published in the Quarterly Journal of the Geological Society on February 14, 1848, the only case of a non Fellow who received that honour.

Women were also great contributors to the popularization of geology. One such example is Mary Somerville. She has been called  “Queen of Nineteenth Century Science.”  She was also the first English geographer. Her book “Physical Geography” (1848) was the first textbook on the subject in English and her most popular work. It was published three years after the first volume of Alexander von Humboldt’s “Cosmos”. Jane Marcet’ Conversations on Chemistry, also gave a basic introduction in chemical mineralogy. Other examples include Delvalle Lowry, who published Conversations on Mineralogy in 1822, and Arabella Buckley, secretary of Charles Lyell, who wrote books about natural history.

Thanks to the pioneer work of these women, the 20th century saw the slow but firm advance of women from the periphery of science towards the center of it.

 

 

References:

BUREK, C. V. & HIGGS, B. (eds) The Role of Women in the History of Geology. Geological Society, London, Special Publications, 281, 1–8. DOI: 10.1144/SP281.1.

Kölbl-Ebert, M. (2007). The geological travels of Charles Lyell, Charlotte Murchison and Roderick Impey Murchison in France and northern Italy (1828). Geological Society, London, Special Publications, 287(1), 109–117.doi:10.1144/sp287.9

Kölbl-Ebert M (2002): British Geology in the Early 19th Century – A Conglomerate with a Female Matrix.– Earth Sciences History 21(1): 3–25.