High variation in postnatal development of Early Dinosaurs.

Cleveland Museum of Natural History Coelophysis block, originally AMNH Block XII collected in 1948 by Colbert and crew

Cleveland Museum of Natural History Coelophysis block, originally AMNH Block XII collected in 1948 (From Wikimedia Commons)

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. They are members of the theropod dinosaur subgroup Coelurosauria, a diverse clade that includes tyrannosauroids and dromaeosaurids, among others. Features like “hollow” bones and postcranial skeletal pneumaticity, feathers, a unique forelimb digit formula, endothermy, and rapid growth rate arose in non-avian dinosaurs in a gradual process occurring over tens of millions of years.

In contrast with all other living reptiles, birds grow extremely fast and possess unusually low levels of intraspecific variation during postnatal development, suggesting that this avian style of development must have evolved after its most recent common ancestor with crocodylians but before the origin of Aves. Most studies indicates that the low levels of variation that characterize avian ontogeny were present in close non-avian relatives as well.

Two C. bauri casts mounted at the Denver Museum of Nature and Science (From Wikimedia Commons)

Two C. bauri casts mounted at the Denver Museum of Nature and Science (From Wikimedia Commons)

Compared with birds, the theropod Coelophysis bauri possess a large amount of intraspecific variation. Coelophysis bauri is the type species of the genus Coelophysis, a group of small, slenderly-built, ground-dwelling, bipedal carnivores, that lived approximately 203 million years ago during the latter part of the Triassic Period in what is now the southwestern United States. Using this taxon to interpret development among early dinosaurs, geoscientists Christopher Griffin and Sterling Nesbitt discovered that the earliest dinosaurs had a far higher level of variation in growth patterns between individuals than crocodiles and birds. The presence of scars on the bones left from muscle attachment and marks where bones had fused together helped the researchers assess how mature the animals were compared with their size.

Body size and extinction risk have been found to be related in various vertebrate groups, therefore a high level of variation within a species may be advantageous in an ecologically unstable environment and may have contributed to the early success of dinosaurs relative to many pseudosuchian clades in the latest Triassic and through the End-Triassic Mass Extinction into the Early Jurassic.

References:

Christopher T. Griffin and Sterling J. Nesbitt, Anomalously high variation in postnatal development is ancestral for dinosaurs but lost in birds. PNAS 2016 : 1613813113v1-201613813.

Brusatte SL, Lloyd GT, Wang SC, Norell MA (2014) Gradual assembly of avian body plan culminated in rapid rates of evolution across the dinosaur-bird transition. Curr Biol 24(20):2386–2392

Puttick, M. N., Thomas, G. H. and Benton, M. J. (2014), HIGH RATES OF EVOLUTION PRECEDED THE ORIGIN OF BIRDS. Evolution, 68: 1497–1510. doi: 10.1111/evo.12363 A.

A brief introduction to the Early dinosaurs from Argentina.

eoraptor-skeleton

Articulated skeleton of Eoraptor lunensi (From Sereno 2013)

The oldest record of Argentinean dinosaurs comes from the Ischigualasto Formation, NW Argentina, dated from 231.4 Ma to 225.9 Ma. Adolf Stelzner in 1889 published the first data on the geology of Ischigualasto, but it was not until 1911 that Guillermo Bodenbender briefly refers to the fossils of the site. In the early 40′s, Joaquin Frenguelli, initiates a geological survey in the western margin of the basin. Later, in 1943, Angel Cabrera described fragmentary therapsid fossils. However, intensive paleontological study of the Ischigualasto and Chañares Formations, began only in the late 1950s.

The Ischigualasto Formation has 300–700 m of mudstone, sandstone, conglomerate, and basalt, and consists of four lithostratigraphic members which in ascending order include the La Peña Member, the Cancha de Bochas Member, the Valle de la Luna Member, and the Quebrada de la Sal Member. Eight valid species of dinosaurs are known from the Ischigualasto Formation: Pisanosaurus mertii, Herrerasaurus ischigualastensis, Sanjuansaurus gordilloi, Eodromaeus murphi, Eoraptor lunensis, Panphagia protos, and Chromogisaurus novasi.

 

Skull of Herrerasaurus ischigualastensis (Sereno, 2013)

Skull of Herrerasaurus ischigualastensis (Sereno, 2013)

Pisanosaurus mertii is a small specimen, know by an incomplete maxilla and lower jaw fragments bearing teeth, vertebrae, incomplete hind limb, and the impression of the pelvis. Described in 1967 by Rodolfo CasamiquelaPisanosaurus is considered as the oldest known ornithischian.

Herrerasaurus ischigualastensis was described by Osvaldo Reig in 1963. The taxon is one of the best known Triassic dinosaurs and the largest dinosaur of the Ischigualasto Formation. Herrerasaurus was fully bipedal, with strong hind limbs, short thighs and long feet. The skull has a rectangular profile and a transversely narrow snout (Sereno and Novas, 1992). The presence of two sacral vertebrae and lack of brevis fossa made Herrerasaurus, and other herrerasaurids, a controversial group.

Sanjuansaurus gordilloi is similar to Herrerasaurus ischigualastensis, although more gracile and possessing short and straight pubis among other differences (Alcober & Martínez, 2010). It’s known from one specimen that preserves left maxilla, partial axial column, scapulae, left ulna, ungual of manual digit III, partial left ilium and pubis, both femora and tibiae, right fibula, right astragalus and calcaneum, and left metatarsal.

Skull and skeleton of Eodromaeus murphi (PVSJ 560). Scale bar equals 10 cm.

Skull and skeleton of Eodromaeus murphi
(PVSJ 560). Scale bar equals 10 cm.

Eodromaeus murphi is a small species with a total length of about 1.2 metres, known from five specimens. The trunk was long and slender, and forelimbs were shorter than the hindlimbs. The skull is relatively low and lightly built with a relatively spacious antorbital fenestra.  A phylogenetic analysis places Eodromaeus within Theropoda as the sister taxon to Neotheropoda

Eoraptor lunensis is known from eight specimens, including the holotype that preserves most of the skeleton. Eoraptor had a slender body with an estimated weight of about 10 kilograms. The lightly built skull has a slightly enlarged external naris and the premaxilla is observed to have a slender posterolateral process. The long bones of the hind limb have more robust shafts than those of Eodromaeus, although in both genera the tibia remains slightly longer than the femur (Sereno et al., 2013). Initially considered a basal theropod, the sauropodomorph affinity of Eoraptor has been strengthened after the publication of its anatomy in 2013.

Panphagia protos is a small species, known from one partial skeleton including several skull bones, lower jaw, and partial axial skeleton. The specimen is an immature individual with an estimated body length of approximately 1.30 m. It was originally proposed as the most basal sauropodomorph (Martinez and Alcober, 2009)

Chromogisaurus novasi is also similar in size to Eoraptor lunensis. It’s known from a partial skeleton lacking the skull. It includes elements of the front and hind limbs, the pelvis and two caudal vertebrae.

References:

Martín D. EZCURRA & Ricardo N. MARTÍNEZ (2016), Dinosaur precursors and early dinosaurs from Argentina., In book: Historia Evolutiva y Paleobiogeografía de los Vertebrados de América del Sur, Publisher: Contribuciones del MACN, Editors: F. Agnolíin, G.L. Lio, F. Brissón Egli, N.R. Chimento, F. Novas, pp.97-107

Reig, O.A. (1963). “La presencia de dinosaurios saurisquios en los “Estratos de Ischigualasto” (Mesotriásico Superior) de las provincias de San Juan y La Rioja (República Argentina)”. Ameghiniana (in Spanish). 3 (1): 3–20.

Sereno, P.C.; Novas, F.E. (1992). “The complete skull and skeleton of an early dinosaur”. Science. 258 (5085): 1137–1140.

Ricardo N. Martinez; Paul C. Sereno; Oscar A. Alcober; Carina E. Colombi; Paul R. Renne; Isabel P. Montañez; Brian S. Currie (2011). “A Basal Dinosaur from the Dawn of the Dinosaur Era in Southwestern Pangaea”. Science. 331 (6014): 206–210. doi:10.1126/science.1198467

Martinez RN, Alcober OA (2009) A Basal Sauropodomorph (Dinosauria: Saurischia) from the Ischigualasto Formation (Triassic, Carnian) and the Early Evolution of Sauropodomorpha. PLoS ONE 4(2): e4397. doi:10.1371/journal.pone.0004397

Ezcurra, M. D. 2010. “A new early dinosaur (Saurischia: Sauropodomorpha) from the Late Triassic of Argentina: a reassessment of dinosaur origin and phylogeny.” Journal of Systematic Palaeontology 8: 371-425.

 

Dracorex hogwartsia: A fantastic beast and where to find it.

The cover of the book Fantastic Beasts and Where to Find Them.

The cover of the book Fantastic Beasts and Where to Find Them.

It has been nearly 20 years since Harry Potter and The Philosopher’s Stone was released. Written by  J. K. Rowling, the book was the first of a saga about a young wizard, Harry Potter, and his friends Hermione Granger and Ron Weasley, all of whom are students at Hogwarts School of Witchcraft and Wizardry. The original seven books were adapted into an eight-part film series. In 2011, the last part of the saga, Harry Potter and the Deathly Hallows Part 2 debuted in cinemas worldwide. Now, the magic world of Harry Potter is returning to the big screen. “Fantastic Beasts and where to find it” takes place in the Harry Potter Universe almost 80 years before Harry himself enters the scene. The story follows Newt Scamander, a British wizard and magic-zoologist. After being expelled from Hogwarts, Scamander joined to the Ministry of Magic and spent two years in the Office for House-Elf Relocation before being transferred to the Beast Division. Due to his extensive knowledge of magical creatures, Augustus Worme of Obscurus Books commissioned Scamander to write the first edition of “Fantastic Beasts and Where to Find Them”.

Dracorex skeletal reconstruction (Dracorex hogwartsia) is in the permanent collection of The Children’s Museum of Indianapolis.

Skeletal reconstruction of Dracorex hogwartsia in the permanent collection of The Children’s Museum of Indianapolis (From Wikimedia Commons)

Scamander travelled to numerous cities doing research for his book and in 1926 he arrived to New York, a city full of great economic inequality and where wizards were forced to hide. Years later, Scamander worked extensively with the Dragon Research and Restraint Bureau, which led him on expeditions all over the world, collecting information for new editions of Fantastic Beasts. Published in 1927, Fantastic Beasts became an approved textbook at Hogwarts. Among the beasts included in the book are Acromantula, the Basilisk, Manticore and different types of Dragons. Most probably, Scamander would have included Dracorex hogwartsia in a new edition of the book.

Dracorex is known from one nearly complete skull discovered in the Upper Cretaceous Hell Creek Formation of South Dakota and donated to the Children’s Museum of Indianapolis in 2004. It was described by Bob Bakker and Robert Sullivan in 2006. The  name was taken from the Latin words for dragon, draco, and king, rex, and the latinized name for Hogwarts, hogwartsia. 

Dracorex skull (Image credit: The Children’s Museum of Indianapolis)

Dracorex skull (Image credit: The Children’s Museum of Indianapolis)

Dracorex is a dinosaur genus of the family Pachycephalosauridae, a diverse group of small, herbivorous dinosaurs, characterized by short forelimbs, stocky and powerful hind limbs, and a short, thick neck. Their most distinguishing feature was the development of a cranial dome, which is formed by the fusion and thickening of the frontals and parietals, and in some species, peripheral bones of the skull roof. Their remains are known from the Late Cretaceous of North America, Asia, and possibly Europe. The group include Pachycephalosaurus, Stegoceras, Stygimoloch and Prenocephale

Dracorex is similar to Pachycephalosaurus and Stygimoloch, but differs from them in having a flat skull, four-spiked squamosals, enlarged supratemporal fenestrae and a skull covered entirely with dermal ossicles (knobs, rugosities, and spikes). In a paper published in 2009 , it was suggested that “Dracorex” and “Stygimoloch” represent younger ontogenetic stages of Pachycephalosaurus. 

 

References:

Bakker, R. T., Sullivan, R. M., Porter, V., Larson, P. and Saulsbury, S.J. (2006). “Dracorex hogwartsia, n. gen., n. sp., a spiked, flat-headed pachycephalosaurid dinosaur from the Upper Cretaceous Hell Creek Formation of South Dakota.” in Lucas, S. G. and Sullivan, R. M., eds., Late Cretaceous vertebrates from the Western Interior. New Mexico Museum of Natural History and Science Bulletin 35, pp. 331–345. 

Horner J.R. and Goodwin, M.B. (2009). “Extreme cranial ontogeny in the Upper Cretaceous Dinosaur Pachycephalosaurus.” PLoS ONE, 4(10): e7626

Newt Scamander. Fantastic Beasts & Where to Find Them. New York, NY: Arthur A. Levine Books, 2001

A Unique Late Triassic Dinosauromorph Assemblage from Brazil

The skull of Buriolestes shultzi. (Image credit: Cabreira et al., 2016)

The skull of Buriolestes shultzi. (Image credit: Cabreira et al., 2016)

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, respectively represented by new species of Lagerpetidae and Sauropodomorph.

The lagerpetids, a family of basal dinosauromorphs, are represented by a semi-articulated skeleton and a pair of fragmentary femora. As for the dinosaurs, a large articulated individual was preserved, together with smaller and non-duplicated bone elements that indicate the presence of another individual The two articulated specimens are named  Ixalerpeton polesinensis and Buriolestes shultzi.

Ixalerpeton polesinensis helps to define traits of anatomical parts previously unknown for lagerpetids. For example, a skull roof broader than that of most early dinosaurs, an anterior tympanic recess in the braincase, as is typical of Dinosauriforme, although retains traits unknown to that group, such as a large post-temporal fenestra, a postfrontal bone, and a frontal not excavated by the supratemporal fossa.

A: Skeletal reconstruction of Ixalerpeton polesinensis. B: Skull roof. C: Braincase. (Adapted from Cabreira et al., 2016)

A: Skeletal reconstruction of Ixalerpeton polesinensis. B: Skull roof. C: Braincase. Abbreviations: f, frontal; fm, foramen magnum; p, parietal; pof, postfrontal; pp, paroccipital process; so, supraoccipital. (Adapted from Cabreira et al., 2016)

 

Buriolestes shultzi is the earliest member of Sauropodomorpha, although lacks usual sauropodomorph traits such as a reduced skull and an enlarged external naris, and as in all early dinosaurs, the frontal is excavated by the supratemporal fossa. As typical of sauropodomorphs, the humerus is longer than 60% the length of the femur, and the deltopectoral crest extends for more than 40% of its length. The dentary traits are compatible with a faunivorous diet suggesting that early members of the Sauropodomorpha were likely predators.

The fossils, found by a team from the Lutheran University of Brazil, confirms that the co-occurrence between non-dinosaurian Dinosauromorpha and dinosaurs was not restricted to later stages of the Triassic and to the northern parts of Pangaea, suggesting that a rapid replacement was a very unlikely scenario for the initial radiation of dinosaurs.

References:

Cabreira et al., A Unique Late Triassic Dinosauromorph Assemblage Reveals Dinosaur Ancestral Anatomy and Diet, Current Biology (2016), http://dx.doi.org/10.1016/j.cub.2016.09.040

Langer, M.C., Nesbitt, S.J., Bittencourt, J.S., and Irmis, R.B. (2013). Non-dinosaurian Dinosauromorpha. Geol. Soc. Spec. Publ. 379, 157–186.

Halloween special IV: Atlach-Nacha and the Spiders of Leng.

The male, Mongolarachne jurassica, and female, Nephila jurassica, were similar in size. Photo: Kansas University and Paul Selden

The male, Mongolarachne jurassica, and female, Nephila jurassica, were similar in size. Photo: Kansas University and Paul Selden

Clark Ashton Smith (January 13, 1893 – August 14, 1961) was an American poet, sculptor, painter and author of fantasy, horror and science fiction short stories. He was one of the big three of Weird Tales, with Robert E. Howard and H. P. Lovecraft.  His work is marked by an extraordinarily rich and ornate vocabulary, a cosmic perspective and a sardonic humor. Among his numerous contribution to the Cthulhu Mythos is Atlach-Nacha, the spider God, first introduced in “The Seven Geases” (Weird Tales, Vol. 24, No. 4, October 1934). Atlach-Nacha resembles a huge spider with an almost-human face. It dwells within a huge cavern deep beneath Mount Voormithadreth, a mountain in the now vanished kingdom of Hyperborea in the Arctic. The bloated purple spiders of Leng are thought to be its children and servitors.

Dorsal view of a near-complete specimen of Palaeocharinus tuberculatus in Windyfield chert, showing prosoma (Pr), opisthosoma (Op), and the rear three right leg appendages (RL2-4) (scale bar = 1 mm). Image credit: University of Aberdeen

Dorsal view of a near-complete specimen of Palaeocharinus tuberculatus in Windyfield chert, showing prosoma (Pr), opisthosoma (Op), and the rear three right leg appendages (RL2-4) (scale bar = 1 mm). Image credit: University of Aberdeen

From Greek mythology to African folklore, the spider has been used to represent a variety of things, and gained a reputation for causing irrational fear in humans. Among the oldest known land arthropods are Trigonotarbids, an extinct order of terrestrial arachnids related to modern day spiders. The earliest trigonotarbid known in the fossil record is from the Silurian Ludlow Bone Bed. In 1923, Stanley Hirst described five species of trigonotarbids from the Rhynie cherts under the generic names Palaeocharinoides and Palaeocharinus. These are Palaeocharinoides hornei, Palaeocharinus rhyniensis, P. scourfieldi, P.calmani and P. kidstoni.

Spiders (Order Araneae) are massively abundant generalist arthropod predators that are found in nearly every ecosystem on the planet since the Devonian (>380 mya). The oldest true spiders belonged to the Mesothelae. Mongolarachne jurassica, from Daohuogo, Inner Mongolia in China, is the largest known fossil spider. Mongolarachne is remarkable for being larger than its female counterpart, Nephila jurassica, found on the same site in 2011.

 

References:

Garrison, Nicole L.; Rodriguez, Juanita; Agnarsson, Ingi; Coddington, Jonathan A.; Griswold, Charles E.; Hamilton, Christopher A.; Hedin, Marshal; Kocot, Kevin M.; Ledford, Joel M.; Bond, Jason E. (2016). “Spider phylogenomics: untangling the Spider Tree of Life”. PeerJ. 4: e1719. doi:10.7717/peerj.1719

Garwood, Russell J.; Dunlop, Jason (July 2014). “The walking dead: Blender as a tool for paleontologists with a case study on extinct arachnids”. Journal of Paleontology. Paleontological Society. 88 (4): 735–746. doi:10.1666/13-088

 

Fossilized dinosaur brain tissue identified

Computer animation of a fossilized dinosaur brain (Credit: University of Manchester)

Computer animation of a fossilized dinosaur brain (Credit: University of Manchester)

Our knowledge of dinosaurian braincases and the structure of their endocranial cavities has a surprisingly long history. The first well-preserved braincase (NHMUK R2501) was found almost 150 years ago in the Isle of Wight and was described as probably belonging to Iguanodon. In 1897, Charles William Andrews – using the same specimen – suggested that dinosaurian brains, and in particular their lobes and surface convolutions, were not closely pressed against the cranial wall. Almost sixty years later, John Ostrom published a study on the anatomy of the hadrosaurian dinosaurs of North America and reinforced the general opinion that they had brains that were not packed tightly within the braincase. Previously, Alfred Romer observed that the interior walls of reptile braincases reflect the shape of the brain at an early state of its development. Now, a team of paleontologists from the University of Cambridge and the University of Western Australia uncovered the first fossilized brain tissue from a dinosaur.

The extraordinary specimen is likely to have belonged to a species related to Iguanodon, which lived around 133 million years ago. It was found in 2004 by fossil hunter Jamie Hiscocks, near Bexhill in Sussex. Fossilized footprints and trackways of Iguanodon-like ornithopods were found at a similar stratigraphic level.

Images of (a) the Bexhill iguanodontian natural endocast specimen and (b) a computed tomography. Scale bar: 10 mm (From Brasier et al., 2016)

Images of (a) the Bexhill iguanodontian natural endocast specimen and (b) a computed tomography. Scale bar: 10 mm (From Brasier et al., 2016)

The natural cranial endocast was unusually well preserved along its dorsolateral flanks, corresponding to the approximate position of the cerebellum. A scanning electron microscopy (SEM) revealed detailed structures, interpreted as meningeal fabrics, blood vessels and potentially superficial cortical tissues, which have been replaced by calcium phosphate or moulded by microcrystalline iron carbonate. The meningeal structures show similarities with those seen in crocodiles and birds. The areas occupied by the forebrain lobes and hypothalamus were well developed, so it’s reasonable to suppose that iguanodontian dinosaurs of this type had moderately complex behaviour similar to modern crocodilians.

To preserve soft tissue as phosphate is necessary a locally anoxic environment to promote bacterially mediated mineralization. Under freshwater conditions, eutrophication adds phosphate to the water column in the form of a phosphoric acid series that reduce the pH of the water, rapidly fixing soft tissues, and dissolving the surrounding mineralized tissues. As result, the soft tissues associated with the brain could have been preserved and cast prior to complete burial by sediment (Brasier et al., 2016).

References:

Martin D. Brasier et al.’ Remarkable preservation of brain tissues in an Early Cretaceous iguanodontian dinosaur.’ Earth System Evolution and Early Life: a Celebration of the Work of Martin Brasier. Geological Society, London, Special Publications, 448. (2016). DOI: 10.1144/SP448.3
Ostrom, J.H. 1961. Cranial anatomy of the hadrosaurian dinosaurs of North America. Bulletin of the American Museum of Natural History, 122, 35–196

Forgotten women of Paleontology: The Newnham quartet.

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Ethel Skeat (right) and Margaret Crosfield (middle) at Oswestry, 1908 (From Burek and Malpas, 2007)

Women have played  various and extensive roles in the history of geology. In the 18th and 19th centuries women’s access to science was limited, and science was usually a ‘hobby’ for intelligent wealthy women. They collected fossils and mineral specimens, and were allowed to attend scientific lectures, but they were barred from membership in scientific societies. It was common for male scientists to have women assistants, often their own wives and daughters. A good example of that was Mary Lyell (1808–1873), daughter of the geologist Leonard Horner and the wife of eminent geologist Charles Lyell. Unfortunately, their contribution has not been widely recognised by the public or academic researchers.

Newnham Hall was founded by Henry Sidgwick in 1875, and was the second Cambridge College to admit women after Girton College. The co-founder of the college was Millicent Garrett Fawcett, primarily known for her work as a suffragist. In 1879, Professor Charles Lapworth, the man who solved the great Cambro-Silurian controversy, encouraged a small group of women at Newnham College to investigate the Silurian and Ordovician rocks of North Wales. Those women were: Gertrude Elles, Ethel Shakespear (née Wood), Ethel Woods (née Skeat) and Margaret Chorley Crosfield.

Newnham began as a house for five students in Regent Street in Cambridge in 1871

Newnham began as a house for five students in Regent Street in Cambridge in 1871

Ethel Gertrude Skeat was born on 14 May, 1865, in Cambridge, England. She was the third daughter of Professor William Walter Skeat. In 1891, she went to Newnham College, Cambridge, at the same time as Gertrude Elles and Ethel Wood. In Newham, she also met  her life-long friend and collaborator, Margaret Crosfield. She completed the Natural Science Tripos certificate part 1, gaining a Class 1 at the age of 29, but without being awarded a degree. In 1893, she joined the Geologists’ Association (GA) and collaborated with her long-time friend, Margaret Crosfield, on their first paper on Welsh stratigraphy in the Carmarthen area, which was published in the Quarterly Journal of the Geological Society in 1896. Ethel won a Bathurst Studentship which she used to go to Munich to work with Karl Alfred von Zittel. She was the first woman to be admitted as a guest to scientific lectures at Munich University after a petition by Professor Zittel. She also collaborated with Victor Madsen on an important work on the Glacial Boulders of the Mesozoic of Denmark. In 1908, she was awarded the Murchison Fund by the Geological Society of London and became the 8th woman to receive any kind of funding from the Geological Society . In 1911, a few months after her marriage with Henry Woods, she became a lecturer at the Cambridge Training College for Women and remained there for 2 years. She died on 26 January 1939 in Meldreth, England.

Margaret Crosfield on a Geologists’ Association fieldtrip to Leith Hill with Professor Lapworth (From Burek and Malpas, 2007).

Margaret Crosfield on a Geologists’ Association field trip to Leith Hill with Professor Lapworth (From Burek and Malpas, 2007).

Margaret Chorley Crosfield was born on 7 September 1859 in Reigate, Surrey. She entered Newnham in 1879 at the age of 20 years but her studies there were interrupted by ill health. She returned to complete her studies 10 years later and with the permission of the authorities she only took geology as a subject. She joined the GA in 1892 and 17 years later she was among the first group of women to be elected Fellows of the Geological Society of London. She published three important papers. The first was on Carmarthen with Ethel Skeat that formed the basis of the geological map produced by the British Geological Survey for the area. In 1914, Margaret published with Mary Johnston a work on the Wenlock limestone of Shropshire. Later, in 1925, she published her second paper with Ethel Skeat (now Mrs. Woods) on the geology of the Silurian rocks of the Clwydian Range. She was also a great promoter of women’s suffrage and some of her field notes are written on the back of suffragette notepaper. She died October 13, 1952.

Dr Gertrude Elles (1872-1960), pioneer woman geologist (Image: Sedgwick Museum archives)

Dr Gertrude Elles (1872-1960), pioneer woman geologist (Image: Sedgwick Museum archives)

Gertrude Lilian Elles was born in Wimbledon on 8 October 1872. She attended Newnham College, Cambridge, at the age of 19 and studied under the guidance of Thomas McKenny Hughes and John Edward Marr, two of the leading geologists of the period. She travelled to Trinity College, Dublin, as one of the ‘Steamboat Women’ to receive her DSc in 1905. Elles was a field geologist, stratigrapher and palaeontologist. Her major work concerned the interpretation of graptolite zones of Lower Palaeozoic strata. Graptolites are extinct marine creatures that formed net-like colonies composed of one or more branches. In the late 1890s, she and her Newnham friend and colleague Ethel Wood began the preparation of British Graptolites (1901-1918), a monograph which was produced in parts over the next twenty years under the general editorship of  Professor Charles Lapworth. In 1919 she won the Murchison Medal and became one of the first female Fellows of the Geological Society. She had not an official university position at Cambridge until 1926 when she was appointed to a university lectureship. Ten years later, she became the first woman Reader. She died on November 18, 1960.

Ethel Wood (1871–1945)

Ethel Wood (1871–1945).

Ethel Reader Wood was born on on 17 July 1871 at Biddenham, near Bedford. Her lifelong friendship with Gertrude Elles began in 1891 when she went up to Newnham College where she obtained a First Class degree specializing in geology. Her first work was a study of rocks in the Lake District, suggested by Professor Marr and undertaken jointly with Elles. The results were published in the Geological Magazine in 1895. A year later, she went to Birmingham University as research assistant to Charles Lapworth. Two of her own publications from this period were especially important. The first was a 1900 paper on the Ludlow formations. The second was her paper on the Tarannon series published in 1906, almost a small monograph on those beds, which made plain their stratigraphic relationship to the better-known Upper Llandovery horizon. In 1904 she won the Wollaston Fund from the Geological Society and the following year she was elected an Associate of Newnham College. She became a Fellow of the Geological Society in 1919 and the following year, shortly after the last part of the monograph came out, was awarded the Murchison Medal. Like Marie Stopes, she gained national recognition not for her geological work but for her social activities, specifically her efforts during World War I. For her public service she received an MBE in 1918 and a DBE in 1920. She died of cancer in 1946.

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., and J.A. Malpas, (2007). “Rediscovering and conserving the Lower Paleolithic ‘treasures’ of Ethel Woods (née Skeat) and Margaret Crosfield in northeast Wales.” In Cynthia V. Burek and Bettie Higgs, eds., The Role of Women in the History of Geology. London: Geological Society, Special Publications, vol. 281, pp. 203–226.

C. V. Burek (2007). The role of women in geological higher education – Bedford College, London (Catherine Raisin) and Newnham College, Cambridge, UK, Geological Society, London, Special Publications, eds Burek C. V., Higgs B. 281, pp 9–38. 

Creese, Mary R. S.; Creese, Thomas M. (2009). “British women who contributed to research in the geological sciences in the nineteenth century”. The British Journal for the History of Science. 27 (01): 23. doi:10.1017/S0007087400031654

An avian vocal organ from the Mesozoic.

The Vegavis iaai specimen showing the location of the syrinx. (Adapted from Clarke et al., 2016)

The Vegavis iaai specimen showing the location of the syrinx. (Adapted from Clarke et al., 2016)

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 of theropods and early birds have filled the morphological, functional, and temporal gaps along the line to modern birds. The earliest diversification of extant birds (Neornithes) occurred during the Cretaceous period and 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. Today, with more than 10500 living species, birds are the most species-rich class of tetrapod vertebrates.

In the mid-nineteenth century, T. H. Huxley recognized that birds were most closely related to dinosaurs. He also named the unique vocal organ in birds as the syrinx. Located at the base of a bird’s trachea, the syrinx consists of specialised cartilaginous structures, connective tissue masses, membranes and muscles. The oldest known remains of a syrinx was found within the fossilised, partial skeleton of a bird, known as Vegavis iaai, from the Late Cretaceous (66 mya) of Antarctica.

Vegavis iaai by Gabriel Lio. / Photo: CONICET

Vegavis iaai by Gabriel Lio. / Photo: CONICET

The Vegavis iaai holotype specimen from Vega Island, western Antarctica, was discovered in 1992 by a team from the Argentine Antarctic Institute, but was only described as a new species in 2005 (Clarke et al., 2005). It belonged to the clade Anseriformes, a group that includes ducks, geese and swans. Vegavis exhibits the fusion of cartilage rings and asymmetry between the left and right sides of the syrinx, that are useful for making comparisons with structural data from the present-day birds. Fused rings in Vegavis form a well-mineralized pessulus, a derived neognath bird feature, proposed to anchor enlarged vocal folds or labia. Although mineralized structures of the syrinx in Vegavis and many parts of extant Anatidae show asymmetry, Presbyornis, Chauna and Galliformes lack this feature. The absence of known tracheobronchial remains in all other Mesozoic dinosaurs may be indicative that a complex syrinx was a late arising feature in the evolution of birds, well after the origin of flight and respiratory innovations.

 

References:

Julia A. Clarke, Sankar Chatterjee, Zhiheng Li, Tobias Riede, Federico Agnolin, Franz Goller, Marcelo P. Isasi, Daniel R. Martinioni, Francisco J. Mussel and Fernando E. Novas. Fossil evidence of the avian vocal organ from the Mesozoic. Nature, 2016 DOI: 10.1038/nature19852

Clarke, J. A., C. P. Tambussi, J. I. Noriega, G. M. Erickson, and R. A. Ketcham. 2005. Definitive fossil evidence for the extant avian radiation in the Cretaceous. Nature 433:305-308.

Larsen, O. N.; Franz Goller (2002). “Direct observation of syringeal muscle function in songbirds and a parrot”. The Journal of Experimental Biology. 205 (Pt 1): 25–35.

Xing Xu, Zhonghe Zhou, Robert Dudley, Susan Mackem, Cheng-Ming Chuong, Gregory M. Erickson, David J. Varricchio, An integrative approach to understanding bird origins, Science, Vol. 346 no. 6215, DOI: 10.1126/science.1253293.

A brief history of Pterosaurs.

 

Holotype specimen of Pterodactylus antiquus,

Pterodactylus antiquus, Carnegie Museum of Natural History, Pittsburgh, Pennsylvania, USA (From Wikipedia Commons)

In 1784, Cosimo Alessandro Collini, a former secretary of Voltaire and curator of the natural history cabinet of Karl Theodor, Elector of Palatinate and Bavaria, published the first scientific description of a pterosaur. The specimen came from one of the main sources of such fossils, the Late Jurassic lithographic limestones of northern Bavaria, and Collini, after much deliberation, interpreted it as the skeleton of an unknown marine creature. In 1801, on the basis of Collini’s description, George Cuvier identified the mysterious animal as a flying reptile. He later coined the name “Ptero-Dactyle”. This discovery marked the beginning of pterosaur research.

Pterosaurs are an extinct monophyletic clade of ornithodiran archosauromorph reptiles from the Late Triassic to Late Cretaceous. The group achieved high levels of morphologic and taxonomic diversity during the Mesozoic, with more than 150 species recognized so far. Pterosaurs have traditionally been divided into two major groups, “rhamphorhynchoids” and “pterodactyloids”. Rhamphorhynchoids are characterized by a long tail, and short neck and metacarpus. Pterodactyloids have a much larger body size range, an elongated neck and metacarpus, and a relatively short tail. Darwinopterus from the early Late Jurassic of China appear to be a transitionary stage that partially fills the morphological gap between rhamphorhynchoids and pterodactyloids.

The fossil remains of the animal kingdom London :Whittaker, Treacher,1830. http://biodiversitylibrary.org/item/111771

The holotype specimen of Dimorphodon macronyx found by Mary Anning in 1828 (From Wikimedia Commons)

The second pterosaur to be discovered also came from the Solnhofen Limestone and was named Ornithocephalus brevirostris by Samuel Thomas von Sömmerring in 1817. The specimen was even smaller than Pterodactylus antiquus, with a wingspan of only 25 cm. On December of 1828, Mary Anning found the first pterosaur skeleton outside Germany. William Buckland made the announcement of Mary’s discovery in the Geological Society of London and named Pterodactylus macronyx in allusion to its large claws. The animal had a wingspan of around 1.4 m with an elongate tail. The specimen was twice the size of Pterodactylus antiquus. The skull of Anning’s specimen had not been discovered, but Buckland thought that the fragment of jaw in the collection of the Philpot sisters of Lyme belonged to a pterosaur. In the 1850s, another specimen was found, this time with a skull at Lyme and another skull was found later. The skulls of the Lyme Regis pterosaurs bore no resemblance to those of the Solnhofen Limestone in Germany, so Richard Owen erected the new generic name Dimorphodon (Martill, 2013).

Water colour by the Reverend G. E. Howman (From Martill 2015)

Water colour by the Reverend G. E. Howman (From Martill 2015)

In 1829 the Reverend George Howman painted the earliest restoration of a pterosaur. The watercolour also incorporates a ruined castle and a ship, but amazingly predicts aspects of the anatomy of pterosaurs not brought to light by fossils discovered until a few decades later. There’s little doubt that the watercolour by Howman was intended to represent the Pterodactylus discovered by Mary Anning. A label on the back of the work reads: ‘By the Revd G. Howman from Dr [Burckhardt’s] account of a flying dragon found at Lyme Regis supposed to be noctivagous’ . The watercolour Duria Antiqior by Henry de la Beche, also represents several pterosaurs flitting over a scene of ichthyosaur and plesiosaur, representing the Liassic Sea based on fossils found by Mary Anning.

Skull of Pteranodon sp. in the American Museum of Natural History (From Wikipedia Commons)

Skull of Pteranodon sp. in the American Museum of Natural History (From Wikipedia Commons)

In 1845, James Scott Bowerbank exhibited a portion of the snout of ‘a new and gigantic species of Pterodactyl’ at a meeting of the Geological Society of London. The specimen was named Pterodactylus giganteus. He also considered that many of the bones described as avian by Richard Owen, were most likely to be from ‘pterodactyls’.

The discovery of Pteranodon by O.C. Marsh in 1870, eclipsed previous pterosaur discoveries. Pteranodon was the first pterosaur found outside of Europe. Marsh’s discoveries were made in the Late Cretaceous Smoky Hill Chalk deposits of western Kansas. Prior to this discovery, the largest pterosaur fossils known were fragmentary remains from the Cretaceous Chalk of southern England. Edward Drinker Cope, Marsh’s rival, also unearthed several specimens of large North American pterosaur.

Quetzalcoatlus skeleton. (Image Credit: Texas Tech University)

Quetzalcoatlus skeleton. (Image Credit: Texas Tech University)

The first evidence of non-American pterosaurs that rivalled Pteranodon in size was made by C. A. Arambourg around 1940. The specimen was named Titanopteryx philidelphiae. But it was not until the 1970s, that relatively frequent discoveries of giant pterosaurs began again. In 1971,  Douglas A. Lawson, a geology graduate student from the University of Texas, found a 544-mm long humerus and other elements of a huge wing in the Maastrichtian Javelina Formation of Texas. The specimen was named Quetzalcoatlus after the Mexican deity Quetzalcoatl, who was worshipped by the Aztecs in the form of a feathered snake. In 1975, Lawson reidentified Arambourg’s pterosaur metacarpal as a cervical vertebra from a Quetzalcoatlus-like animal, and one with similar proportions to Quetzalcoatlus northropi.

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Illustration from the original serialization of The Lost World.

Jules Verne was the first to introduce Pterosaurs into popular fiction in his novel ”Journey to the Centre of the Earth”, published in France in 1874. In “The Lost World” written by Sir Arthur Conan Doyle, which appeared in The Strand Magazine from April through November of 1912, pterosaurs are central figures. At the beginning of the novel, Professor George Edward Challenger claims to have captured and subsequently lost, a living specimen in South America. After being ridiculed for years, he invites E. Malone, a reporter for the Daily Gazette, Professor Summerlee and Lord John Roxton, an adventurer who knows the Amazon to join him to a trip to South America and prove his story. Later, the crew were attacked by pterodactyls in a swamp. Doyle compares the place with one of the Seven Circles of Dante and described as followed: “The place was a rookery of pterodactyls. There were hundreds of them congregated within view. All the bottom area round the water-edge was alive with their young ones, and with hideous mothers brooding upon their leathery, yellowish eggs”. Doyle completes the scenes by describing the males: “Their huge, membranous wings were closed by folding their fore-arms, so that they sat like gigantic old women, wrapped in hideous web-coloured shawls, and with their ferocious heads protruding above them. Large and small, not less than a thousand of these filthy creatures lay in the hollow before us”.

The Lost World novel has been so immensely popular that it has had a lasting effect, and has contributed significantly to the fascination with dinosaurs and pterodactyls. In 1994, Arthurdactylus a genus of pterodactyloid pterosaur from the Lower Cretaceous  of Brazil was named in honor of Arthur Conan Doyle.

References:

Martill, D.M., 2010. The early history of pterosaur discovery in Great Britain. In: Moody, R.T.J., Buffetaut, E., Naish, D., Martill, D.M. (Eds.), Dinosaurs and Other Extinct Saurians: A Historical Perspective. Geological Society, London, Special Publications 343, 287–311.

Martill, D.M., Dimorphodon and the Reverend George Howman’s noctivagous flying dragon: the earliest restoration of a pterosaur in its natural habitat. Proc. Geol. Assoc. (2013), http://dx.doi.org/10.1016/j.pgeola.2013.03.003

Martill, D. M, and Pointon, Tony, Dr Arthur Conan Doyle’s contribution to the popularity of pterodactyls, Geological Society, London, Special Publications, 375, 2013, doi:10.1144/SP375.19

WITTON, M. P., 2010 Pteranodon and beyond: the history of giant pterosaurs from 1870 onwards. In: Moody, R.T.J., Buffetaut, E., Naish, D., Martill, D.M. (Eds.), Dinosaurs and Other Extinct Saurians: A Historical Perspective. Geological Society, London, Special Publications 343, 287–311.

P. Taquet, K. Padian, The earliest known restoration of a pterosaur and the philosophical origins of Cuvier’s Ossemens Fossiles, C. R. Palevol 3 (2004).

The Early Aptian Oceanic Anoxic Event.

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The Early Cretaceous (Aptian Age), 120 Ma.

The geological records show that large and rapid global warming events occurred repeatedly during the course of Earth history. The growing concern about modern climate change has accentuated interest in understanding the causes and consequences of these ancient abrupt warming events. The early Aptian Oceanic Anoxic Event (OAE1a, 120 Ma) represents a geologically brief time interval characterized by rapid global warming, dramatic changes in ocean circulation including widespread oxygen deficiency, and profound changes in marine biotas. During the event, black shales were deposited in all the main ocean basins. It was also associated with the calcification crisis of the nannoconids, the most ubiquitous planktic calcifiers during the Early Cretaceous. Their near disappearance is one of the most significant events in the nannoplankton fossil record.

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Scanning electron microscope photos of different nannofossil assemblages from Early Cretaceous chalks from the North Sea (adapted from Mutterlose & Bottini, 2013)

Calcareous nannoplankton represent a major component of oceanic phytoplankton. Their calcareous skeletons can be found in fine-grained pelagic sediments in high concentrations and the biomineralization of coccoliths is a globally significant rock-forming process. The ‘nannoconid decline’ is related to the emplacement of the Ontong Java Plateau (OJP). The  CO2 released by the flood basalts was the main player in the climatic events. However, records from the Pacific and Tethys realms demonstrate that during OAE 1a the  major shift in global oceanic osmium composition occurs well after the onset of the nannoconid crisis. Previous studies argued that the nannoconid crisis was caused by ocean acidification due to numerous pulses of CO2 and methane. The Ontong Java Plateau is a massive, submerged seafloor.  It covers an area of about 1,900,000 square kilometers. It  was emplaced ca. 120 Ma, with a much smaller magmatic pulse of ca. 90 Ma. The CO2 release was too late, and too gradual, to have caused the calcification crisis in the nannoconids by ocean acidification

References:

Naafs, B. D. A. et al., Gradual and sustained carbon dioxide release during Aptian Oceanic Anoxic Event 1a, Nature Geosci. http://dx.doi.org/10.1038/ngeo2627 (2016)

Jenkyns, H. C. (2010), Geochemistry of oceanic anoxic events, Geochem. Geophys. Geosyst., 11, Q03004, doi:10.1029/2009GC002788.