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

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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.

Introducing Notatesseraeraptor frickensis.

Notatesseraeraptor frickensis at the Sauriermuseum Frick. (From Wikimedia Commons)

Over the last two decades our knowledge of the fossil record of early theropod dinosaurs has greatly improved. However, there are different hypotheses about their relationships. Theropods are relatively abundant in post-Carnian Triassic faunas, including the European Liliensternus, the South American Zupaysaurus, and the North American Coelophysis. Those taxons represent the earliest major radiation of Neotheropoda. Two primitive branches of this clade are the Coelophysoidea and the Dilophosauridae. More recent studies suggest that at least some members of the ‘traditional Coelophsoidea’ are more closely related to the tetanurans and that the Dilophosauridae may represent a second clade of early non-averostran neotheropods. Notatesseraeraptor frickensis gen. et sp, from the Late Triassic of Switzerland, provides new clues about the relationships of the early theropods.

The new 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 genus name derives from the Latin “nota” meaning feature and “tesserae”, a word used to describe glass, or other material used in the construction of a mosaic, in reference to the interesting mixture of characters found in the fossil.

Skeletal anatomy of N. frickensis gen. et sp. nov. From Zahner and Brinkmann, 2019.

The new specimen was described based on a cranium (SMF 09-2) and partial postcranial skeleton (SMF 06-1). The cranium is proportionally long and low as is commonly found in traditional coelophysoid-grade neotheropods. But in contrast to coelophysids, the premaxillary tooth crowns of N. frickensis are all strongly recurved, laterally compressed and bear fine serrations. 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). The preserved postcranial elements share most of their morphological similarities with ‘Syntarsus’ kayentakatae. N. frickensis has plesiomorphically long forelimbs. The radius is about three-quarters of the length of the humerus. The manus is composed of four digits, whereas the fourth is reduced to a very slim metacarpal. The shape of the ilium are similar to those found in Coelophysis.  

The phylogenetic analyses, with emphasis on early neotheropods, suggests that Notatesseraeraptor is a basal member of Dilophosauridae, a clade that comprises Dilophosaurus, and Cryolophosaurus.

 

References:

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

Martín D. Ezcurra, and Federico L. Agnolín (2017). Gondwanan perspectives: Theropod dinosaurs from western Gondwana. A brief historical overview on the research of Mesozoic theropods in Gondwana. Ameghiniana 54: 483–487. https://doi.org/10.5710/102.054.0501

 

Hesperornithoides miessleriis and the evolution of flight.

Primary blocks of Hesperornithoides specimen WYDICE-DML-001. Images taken by Levi Shinkle. From Hartman et al., 2019.

Birds originated from a theropod lineage more than 150 million years ago. Their evolutionary history is one of the most enduring and fascinating debates in paleontology. In recent years, several discovered fossils as well as innovative studies of living bird behavior, have enriched our understanding of early paravian evolution and flight origins. The discovered fossils demonstrate that distinctive bird characteristics such as feathers, flight, endothermic physiology, unique strategies for reproduction and growth, and a novel pulmonary system have a sequential and stepwise transformational pattern, with many arising early in dinosaur evolution, like the unusually crouched hindlimb for bipedal locomotion,the furcula and the “semilunate” carpal that appeared early in the theropod lineage.

The new paravian theropod, Hesperornithoides miessleriis, from the Late Jurassic Morrison Formation of east–central Wyoming, provides new clues about paravian relationships, as well as the acquisition of flight-related characters in stem avians. Nicknamed “Lori”, and with an estimated length of 89 cm, the new specimen is significantly smaller than other relatively complete theropods from the Morrison Formation. Hesperornithoides lived in a wetland environments with herbaceous plants, but no trees. The habitat, combined with limb proportions indicate that the new specimen was clearly terrestrial.

Association of skeletal elements of Hesperornithoides miessleriis assembled from 3D scans of specimen blocks. Scale bar = 6 cm. From Hartman et al., 2019

Hesperornithoides exhibits the following combination of characters: pneumatic jugal; short posterior lacrimal process; quadrate forms part of lateral margin of paraquadrate foramen; small external mandibular fenestra, humeral entepicondyle >15% of distal humeral width; manual ungual III subequal in size to ungual II; mediodistal corner of tibia exposed anteriorly. The holotype (WYDICE-DML-001) is a partially articulated skeleton consisting of an almost articulated skull, five cervical vertebrae, isolated anterior dorsal rib, portions of 12 caudal vertebrae, five chevrons, partial left scapula and coracoid, portions of the proximal left humerus and distal right humerus, left ulna and radius, radiale, semilunate carpal, left metacarpals I–III, manual phalanges III-2 and 3, manual unguals I, II, and III, ilial fragment, most of an incomplete femur, right and left tibiae and fibulae, left astragalus and calcaneum, portions of right and left metatarsal packets, left pedal phalanges III-1, III-2, III-3, IV-1, IV-2, IV-3, IV-4, and pedal unguals II and III and the proximal portion of IV. The cranial elements are preserved in a separate “skull block”, whereas the axial skeleton is distributed across three blocks.

The acquisition of powered flight in birds was preceded in the course of paravian evolution by a complex sequence of anatomical and functional innovations, and many characters associated with avian flight evolved in a terrestrial context. For this reason, a refined and robust phylogeny of paravians is imperative in order to elucidate the sequence of evolutionary stages that resulted in the acquisition of major avian traits.

 

References:

Hartman S, Mortimer M, Wahl WR, Lomax DR, Lippincott J, Lovelace DM. 2019A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flightPeerJ 7:e7247 https://doi.org/10.7717/peerj.7247

Agnolin FL, Motta MJ, Egli FB, Lo Coco G, Novas FE. 2019. Paravian phylogeny and the dinosaur-bird transition: an overview. Frontiers in Earth Science 6:252 https://www.frontiersin.org/articles/10.3389/feart.2018.00252/full

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

Forgotten women of paleontology: Hildegarde Howard

Hildegard Howard with fossil bird from the Rancho La Brea.

The birth of modern science was hostile to women’s participation. The world’s major academies of science were founded in the 17th century: the Royal Society of London (1662), the Paris Académie Royale des Sciences (1666), and the Berlin Akademie der Wissenschaften (1700). Unfortunately, women were not become members of these societies for over 300 years. Yvonne Choquet-Bruhat became the first woman to be elected to the Paris Academy of Science in 1979. Although the Royal Society was less rigid in terms of memberships than the Paris Academy of Science, it was not until 1945 that the first women were admitted as fellows of the Royal Society: the X-ray crystallographer Kathleen Yardley Lonsdale (1903–1971), and biochemist and microbiologist Marjory Stephenson (1885-1948).

Despite the barriers, between 1880 and 1914, some 60 women contributed papers to Royal Society publications. Meanwhile, in the United States, geology was a marginal subject in the curricula of the early women’s colleges until an intense programme was started at Bryn Mawr College in the 1890s.

Hildegard Howard measures specimens from the Rancho La Brea Collection. Image from The Natural History Museum of Los Angeles County Archives.

Florence Bascom was one of the pioneers when geological education at universities became available to women. She received her PhD degree from Johns Hopkins University in 1893 by special dispensation, as women were not admitted officially until 1907; while Carlotta Joaquina Maury attended Cornell University, where she became one of the first women to receive her PhD in paleontology in 1902.

When Hildegarde Howard began attending the Southern Branch of the University of California (now known as the University of California at Los Angeles), women were still barred from scientific societies. She was born on April 3, 1901 in Washington D.C., but moved to Los Angeles at the age of 5. Her main interest was journalism, until she met her first biology instructor, Miss Pirie Davidson. In 1921, Hildegarde obtained a part-time job working for Dr. Chester Stock, sorting bones from Rancho La Brea in the basement of the Los Angeles Museum of History, Science and Art (now known as the Natural History Museum of Los Angeles County). One year later, she went to Berkeley to finish her degree.

Dr. Hildegarde Howard, in her office in 1961.Copyright Natural History Museum of Los Angeles County

In 1928, she obtained her Ph.D. degree. Her dissertation, entitled “The Avifauna of Emeryville Shellmound”, became one of her most popular works, and remained as the principal reference of its kind until the appearance of the first edition of Nomina Anatomica Avium in 1979. She obtained a permanent position with the museum in 1929. Although she was a curator, she did not receive that official title until 1938. Through that decade, she wrote twenty-four papers on fossil birds in the American Southwest. She was promoted to the curator of Avian Paleontology in 1944, and she would serve in that role until 1951, when she was promoted to Chief Curator of Science, She became the first woman to receive the Brewster Medal for outstanding research in ornithology in 1953.

Hildegarde Howard officially retired in 1961, although continued research on fossil birds, publishing her last paper in 1992. During her extraordinary career, Dr. Howard described 3 families, 13 genera, 57 species, and 2 subspecies, and remains highly regarded as one of the foremost experts in her field. She died on February 28, 1998.

 

References:

Campbell Jr., Kenneth. 2000c. “In Memoriam, Hildegarde Howard 1901-1998.” The Auk, vol.117, no.3, 775-779.

 

Introducing Kaijutitan, the strange beast.

The entrance to the town of Rincón de los Sauces.

Since the discovery of dinosaur remains in the Neuquen basin in 1882, Argentina has gained the title of Land of the Giants. The tittle was reinforced by the discoveries of titanosaurs like Argentinosaurus, Dreadnoughtus, Notocolossus, Puertasaurus, and Patagotitan. The study of this diverse group of sauropod dinosaurs embrace an extensive list of important contributions, which started with Richard Lydekker’s pioneering work on Patagonian dinosaurs, and by the classic Friedrich von Huene monograph on Argentinean saurischians and ornithischians.

Titanosaurus were a diverse group of sauropod dinosaurs represented by more than 30 genera, which included all descendants of the more recent common ancestor of Andesaurus and Saltasaurus. The group includes the smallest (e.g. Rinconsaurus, Saltasaurus; with estimated body masses of approximately 6 tonnes) and the largest sauropods known to date. They had their major radiation during the middle Early Cretaceous. The evolution of body mass in this clade is key element to understand sauropod evolution.

 

Cranial elements of MAU-Pv-CM-522/1. From Filippi et al., 2019.

Kaijutitan maui, is the first basal sauropod titanosaur from the Sierra Barrosa Formation (Upper Coniacian, Upper Cretaceous). The holotype (MAU-Pv-CM-522) consists of cranial, axial, and appendicular elements presenting an unique combination of plesiomorphic and apomorphic characters. The generic name Kaijutitan is derived from Kaiju, Japanese word that means “strange beast” or “monster”, and titan, from the Greek “giant”.  The species name refers to the acronym of the Museo Municipal Argentino Urquiza, Rincon de los Sauces, Neuquén, Argentina.

The cranial elements of this specimen include the complete neurocranium (the supraoccipital, exoccipital, left paraoccipital process, left exoccipital-opisthotic-prootic complex, left laterosphenoid and orbitosphoid, and basioccipital-basisphenoid complex). The impossibility of recognizing clear sutures suggest an ontogenetic adult stage of the specimen. One of the most notable autapomorphies exhibited by Kaijutitan is the anterior cervical vertebra with bifid neural spine, a feature usually found in diplodocids and dicraeosaurids. Unfortunately, the femur and humerus of Kaijutitan maui are incomplete, therefore the body mass of this titanosaur can only be estimated by comparison with other titanosauriforms. Kaijutitan would have had a body mass similar or intermediate to that of Giraffatitan (38.000 kg) and Notocolossus (60.398 kg).

 

References:

Filippi, L.S., Salgado, L., Garrido, A.C., A new giant basal titanosaur sauropod in the Upper Cretaceous (Coniacian) of the Neuquén Basin, Argentina, Cretaceous Research, https://doi.org/10.1016/j.cretres.2019.03.008.