The Herrerasaurian Radiation

Image from Ischigualasto Park (http://www.ischigualasto.gob.ar/)

The Triassic beds of Argentina and Brazil play a key role in the understanding of the origin and early diversification of Dinosauria. The first recorded dinosaurs include some predatory forms, such as the herrerasaurids from the lower Ischigualasto Formation in northwestern Argentina, and the Santa Maria formation in southern Brazil. In 1911, Guillermo Bodenbender briefly refers to the fossils of Ischigualasto, but intensive paleontological study of the Ischigualasto and Chañares Formations began only in the late 1950s. In Brazil, the fossil record of Triassic dinosaurs has greatly expanded since the discovery of Staurikosaurus in 1970.

Herrerasauridae is a basal clade of predatory, obligatorily bipedal dinosaurs recorded from the Upper Triassic of Argentina and Brazil. There are putative records of herrerasaurids from the mid-late Norian strata of Europe, North America, and from the Maleri Formation of India. The Herrerasaurid family includes Staurikosaurus, Gnathovorax, Herrerasaurus, Sanjuansaurus and possibly Frenguellisaurus. Staurikosaurus and Gnathovorax were recovered from the Hyperodapedon Assemblage Zone of the Santa Maria Supersequence in southern Brazil, whilst Herrerasaurus and Sanjuansaurus were collected from the lower levels of the Ischigualasto Formation, and Frenguellisaurus (considered by many authors as a junior synonym of Herrerasaurus) was collected from the upper levels of this unit. 

Skull of Herrerasaurus ischigualastensis (Sereno, 2013)

Herrerasaurus ischigualastensis is one of the best known Triassic dinosaurs and the largest dinosaur of the Ischigualasto Formation. It was described by Osvaldo Reig in 1963. 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.

Due to this combination of features, including some traits that are nearly exclusive of theropod dinosaurs (e.g., serrated dentition, grasping hands, pubis with distal pubic boot, distal caudal prezygapophyses elongated), with some remarkable plesiomorphic traits (e.g., primitive-looking pelvic girdle and tarsus), the phylogenetic relationships of herrerasaurs are problematic. Some authors suggested that Herrerasauridae may constitute the sister group to Dinosauria, whereas others proposed theropod affinities for the group. Other proposal indicates that herrerasaurids may constitute a non-Eusaurischia branch of Saurischia.

 

The holotype of Daemonosaurus chauliodus (CM 76821). From Sues et al., 2011.

The putative North American herrerasaurs Tawa, Chindesaurus, Caseosaurus and Daemonosaurus, have been recorded from Norian to Rhaetian beds in different fossil sites in southwestern USA. Chindesaurus, from the Petrified Forest National Park in Arizona, shows several features of herrerasaurian affinities, while Tawa shares with Herrerasaurus, Sanjuansaurus and Gnathovorax several derived features that are considered diagnostic for Herrerasauria. These include: dorsoventrally deep jugal; cervical vertebrae with pronounced ventral keel; atrophied metacarpals IV and V; pubic shaft fan-shaped distally, resulting from the posterior flexion of the lateral margin of pubis; and anteroposteriorly expanded pubic boot. Among the features that Daemonosaurus shares with Herrerasauridae are: a dorsoventrally deep premaxilla, jugal dorsoventrally tall, and fang-shaped maxillary teeth.

The presence of herrerasaurs outside South America during the Late Triassic suggests the group was globally dispersed, contrasting with their apparent South America endemism. Furthermore, the recognition of Daemonosaurus as a herrerasaurian provides evidence that this clade survived into the Rhaetian and the group was likely one of the victims of the end-Triassic mass extinction.

References:

Novas, F.E., Agnolin, F.L., Ezcurra, Martí.D., Müller, R.T., Martinelli, Agustì., Langer, M., Review of the fossil record of early dinosaurs from South America, and its phylogenetic implications, Journal of South American Earth Sciences (2021), doi: https://doi.org/10.1016/j.jsames.2021.103341.

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

Sues, Hans-Dieter, Nesbitt, Sterling J., Berman, David S., and Henrici, Amy C. 2011. “A late-surviving basal theropod dinosaur from the latest Triassic of North America.” Proceedings of the Royal Society B: Biological Sciences 278 (1723):3459– 3464. https://doi.org/10.1098/rspb.2011.0410

Leonardo and the Fossil Whale

Leonardo da Vinci: Self-portrait. From WikimediaCommons.

Leonardo di ser Piero da Vinci was the archetype of the Renaissance Man: artist, architect, musician, mathematician, engineer, inventor, anatomist, naturalist and geologist. A true polymath. He was born on April 15, 1452 in Vinci, a town in the lower valley of the Arno River. The majority of Leonardo’s scientific observations were in the Leicester Codex, a collection of writings from the 16th Century. Several excerpts from the Codex indicate that Leonard uses many ichnological principles that are still valid today.

The Codex Arundel is similar to the Codex Leicester. It was written between 1480 and 1518. In folio 155r, Leonardo recounted an experience in a cave in the Tuscan countryside: “Unable to resist my eager desire and wanting to see the great multitude of the various and strange shapes made by formative nature, and having wandered some distance among gloomy rocks, I came to the entrance of a great cave, in front of which I stood some time, astonished and unaware of such a thing. Bending my back into an arch I rested my tired hand on my knee and held my right hand over my downcast and contracted eyebrows, often bending first one way and then the other, to see whether I could discover anything inside, and this being forbidden by the deep darkness within, and after having remained there some time, two emo-tions arose in me, fear and desire: fear of the threatening dark cave, desire to see whether there were any wondrous thing within it”.

Reproduction of folios 155v (left corner) and 156r (right corner) of the Codex Arundel. From Collareta et al., 2020.

In the next folio, Leonardo described what appears to have been a fossil whale embedded in the walls of a cave:

“O powerful and once-living instrument of formative nature, your great strength of no avail, you must abandon your tranquil life to obey the law which God and time gave to creative nature. Of no avail are your branching, sturdy dorsal fins with which you pursue your prey, plowing your way, tempestuously tearing open the briny waves with your breast.

Oh, how many a time the terrified shoals of dolphins and big tuna fish were seen to flee before your insensate fury, as you lashed with swift, branching fins and forked tail, creating in the sea, mist and sudden tempest that buffeted and submerged ships…

O Time, swift despoiler of created things, how many kings, how many peoples have you undone? How many changes of state and circumstances have followed since thewondrous form of this fish died here in this winding and cavernous recess? Now unmade by time you lie patiently in this closed place with bones stripped and bare, serving as an armature for the mountain placed over you.”

Tuscan Pliocene fossil mysticetes: (a) ʽPelocetus sp.’ from Le Colombaie, near Volterra (original field sketch by G. Capellini, 1879); (b) Idiocetus guicciardinii from Montopoli (osteoanatomical plate reproduced after Capellini 1905). From Collareta et al., 2020.

In the folio 715r of the Codex Atlanticus, Leonardo described the same animal as ‘setoluto’, i.e. pro-vided with bristles – an observation that strongly evokes the presence of baleen, and as such, a positive identification of the ʽmarine monster’ with a baleen whale. A recent study suggests that Leonardo saw a fossil whale and recognised it as such, but the encounter was most likely along the flank of a hill, where cetacean remains from the Tuscan Pliocene are relatively common. Leonardo also made taphonomic observations on it and inferred that a considerable amount of time must have passed from the death of the whale in the marine realm to allow for its eventual discovery on land.

Leonardo’s legacy is extraordinary and his contributions to historical geology and ichnology are of special relevance. He wrote about the original horizontal arrangement of strata before Nicola Steno’s seminal work. He also provided the first organic observations on concepts such as actualism, taphonomy, and palaeocological inference. But because he never received a formal education in Latin or Mathematics, his writings were ignored by the scholars of the time. Five centuries after his death, Leonardo still surprises us.

References:

Collareta, A., Collareta, M., Berta, A., & Bianucci, G. (2020). On Leonardo and a fossil whale: a reappraisal with implications for the early history of palaeontology, Historical Biology, DOI: 10.1080/08912963.2020.1787403.

Etheridge, Kay. “Leonardo and the Whale.” In Leonardo da Vinci – Nature and Architecture,edited by C. Moffat and S.Taglialagamba, 89-106. Leiden: Brill, 2019.

Forgotten women of Paleontology: Maria Pavlova

María Pávlova (1854-1938). From Wikimedia Commons

The first half of the 1860s was an extraordinary time in Russian history. After the Crimean War Tsar Alexander II took  steps to set the Russian Empire on the path of modernization. In 1868, Russian feminists submitted a request to the rector of the St. Petersburg University to open higher women’s course. The rector agreed, but the Minister of Education demoted the status of the courses to “public lectures”. A year later, Julia Lermontova and Sofia Kovalevskaya obtained permission to attend classes at Heidelberg University in Germany. Only in 1876, Alexander II authorized the creation of higher women’s courses with the same curricula as men’s universities. Finally, the University Courses for women opened on October 2, 1878 in St. Petersburg. Historian K. N. Bestuzhev-Rumin was appointed the first director of the courses (in his honor the courses were unofficially called “Bestuzhev’s”).

Maria Vasillievna Pavlova, nee Gortynskaia, was the first Russian woman to achieve significant national and international success in vertebrate paleontology. She was born in Ukraine in 1854. Her father was a state provincial doctor who encouraged her to study science. In 1870, she graduated from the Kiev Institute of Noble Maidens. Three years later she married a rural doctor N.N. Illich-Shishatsky. In the summer of 1880, after the death of her husband she traveled to Paris to attend classes at the Sorbonne. She studied zoology, botany, geology, and paleontology under the guidance of Albert Gaudry, receiving the grade of specialist in paleontology in 1884. She later worked in the Paris Museúm d’historie naturelle. In 1886 she married with the young geologist A.P. Pavlov and returned to Russia. At the request of her husband, Maria was allowed to put in order the paleontological collection of the Geological Cabinet of Moscow University, where she worked for more than 30 years.

M.V. Pavlova at her desk at the Paleontological Museum of Moscow State University. 1920s. From Bessudnova and Lyubina, 2019.

Her first scientific work was a description of the ammonites collected by Pavlov in the Volga region but all of her subsequent research focused on vertebrate fossils. She studied the fossil fauna of the Novaya Zemlya islands, and the “hipparion fauna” of the southwestern regions of European Russia. In 1897 she was one of only two women invited to join the Organizing Committee and presentations of the International Geological Congress (IGC) held in St. Petersburg. Between 1887-1906 the nine issues of her celebrated Studies in the Paleontological History of Hoofed Animals were published. Later she published her monograph Les éléphants fossils de la Russie, followed by her two-volume of Mammifères tertiaires de la nouvelle Russie, co-authored with Aleksei Pavlov. Maria often acquired material for her research from private individuals and exchanged casts of fossil animals with famous foreign paleontologists and museum curators.

In order to introduce paleontology to a wider audience, Maria translated into Russian Henry Neville Hutchinson’s Extinct Monsters and Melchior Neumayer’s Die Stämme des Tierreichs. In 1910, Pavlova was invited to head the department of paleontology at Moscow University. It was the first experience of systematic teaching of paleontology in Moscow. In 1925 she was elected a corresponding member of the Russian Academy of Sciences (in the same year it was renamed into the Academy of Sciences of the USSR). In 1926, the Geological Society of France awarded the Pavlovs with the gold medal  for their geological and paleontological works. She went on her last geological expedition in 1931, to the Volyn district, near Khvalynsk, a place of a mass accumulation of bones of fossil mammoths, elephants and rhinos.

She died on December 23, 1938.

 

References:

Valkova, O. (2008). The Conquest of Science: Women and Science in Russia, 1860–1940. Osiris, 23(1), 136–165. doi:10.1086/591872

Bessudnova Z.A., Lyubina G.I. Main lady of russian paleontology. To the 165th anniversary of the honorary academician Maria V. Pavlova. // Вестник Российской академии наук. – 2019. – Vol. 89. – N. 6. – P. 621-628. doi: 10.31857/S0869-5873896621-628

 

Introducing Llukalkan aliocranianus

Photograph of the materials in the field. Image credit: Federico Gianechini

The Abelisauridae represents the best-known carnivorous dinosaur group from Gondwana. Their fossil remains have been recovered in Argentina, Brazil, Morocco, Niger, Libya, Madagascar, India, and France. The group was erected by Jose Bonaparte with the description of  Abelisaurus Comahuensis. These theropods exhibit spectacular cranial ornamentation in the form of horns and spikes and strongly reduced forelimbs and hands. The Argentinean record of abelisauroid theropods begins in the Middle Jurassic (Eoabelisaurus mefi) and spans most of the Late Cretaceous. The clade includes Carnotaurus sastrei, Abelisaurus comahuensis, Aucasaurus garridoi, Ekrixinatosaurus novasi, Skorpiovenator bustingorryi, Tralkasaurus cuyi and Viavenator exxoni. Llukalkan aliocranianus, a new furileusaurian abelisaurid from the Bajo de la Carpa Formation (Santonian) in northwestern Patagonia, is an important addition to the knowledge of abelisaurid diversity.

 

Reconstruction of the complete skull and mandible of Llukalkan aliocranianus. Scale bar: 5 cm. From Gianechini et al., 2021

The new specimen was found near the site where the remains of Viavenator exxoni were recovered at La Invernada fossil area, 50 km southwest of Rincón de los Sauces city, Neuquén province, Argentina. This site has provided a valuable theropod record. Other taxa discovered at La Invernada include the titanosaurian sauropods Bonitasaura salgadoi, Traukutitan eocaudata, and Rinconsaurus caudamirus, pterosaurs, multiple crocodyliforms, snakes, and turtles.

The holotype (MAU-Pv-LI-581) is an incomplete but partially articulated skull with a complete braincase. The generic name derived from the word Llukalkan, “one who scares or causes fear” in Mapudungun language. The specific name aliocranianus means “different skull” in Latin.  Llukalkan exhibits some similarities with Viavenator, that include: elongate and robust olfactory tracts; large and horizontally oriented olfactory bulbs; cerebral hemispheres clearly delimited in lateral view; a tongue-shaped floccular process of cerebellum posteriorly projected and reaching the level of the posterior semicircular canal; and elongate and ventrally projected passage for the rostral middle cerebral vein. Additionally, Llukalkan has a small pneumatic recess caudal to the columellar recess, which is identified as a poorly developed caudal tympanic recess. This taxon also presents a T-shaped lacrimal with jugal ramus lacking a suborbital process, that differs significantly from the lacrimal of other abelisaurids.

 

References:

Federico A. Gianechini, Ariel H. Méndez, Leonardo S. Filippi, Ariana Paulina-Carabajal, Rubén D. Juárez-Valieri & Alberto C. Garrido (2021): A New Furileusaurian Abelisauridfrom La Invernada (Upper Cretaceous, Santonian, Bajo De La Carpa Formation), NorthernPatagonia, Argentina, Journal of Vertebrate Paleontology, DOI: 10.1080/02724634.2020.1877151

Introducing Ninjatitan zapatai, the earliest known titanosaur

Anterior caudal vertebra of Ninjatitan zapatai. Scale bar equals 10 cm. From Gallina et al., 2021

Titanosauria is the most diverse sauropod clade represented by nearly 80 genera described worldwide, the vast majority of which were recovered from Upper Cretaceous sediments of Argentina. It has been suggested that the titanosaurian origin took place around 135 million years ago in South America. The study of this diverse group of large, long-necked, herbivorous dinosaurs embrace an extensive list of important contributions, which started with Richard Lydekker’s pioneering work on Patagonian dinosaurs.

The discovery of Ninjatitan zapatai, a new specimen from the Lower Cretaceous Bajada Colorada Formation (Berriasian–Valanginian) of north Patagonia, supports the hypothesis that the group was already established in the Southern Hemisphere and reinforces the idea of a Gondwanan origin for Titanosauria. Ninjatitan lived 140 million years ago and reached 20 meters in length (65 feet). The firs remains were discovered in 2014 by technician Jonatan Aroca. The holotype (MMCh-Pv228) includes an incomplete anterior–middle dorsal vertebra, a middle dorsal centrum, and anterior caudal centra with the base of neural arches preserved, a complete left scapula, a fragmentary distal femur, and a nearly complete left fibula of a single individual. The generic name honors the Argentine paleontologist Sebastián “Ninja” Apesteguía. The species name refers to Mr. Rogelio “Mupi” Zapata, in recognition for his work as a technician of the Museo Municipal Ernesto Bachman.

Left scapula of Ninjatitan zapatai. Scale bar equals 10 cm. From Gallina et al., 2021.

Despite the fragmentary nature of the new taxon, three derived characters of Ninjatitan support its possition within the clade Titanosauria: 1) presence of procoelous anterior caudal centra; 2) pneumatized neural arch of anterior caudal vertebrae; and 3) position of the acromial process near the glenoid level. The position of Ninjatitan, as a basal titanosaur, extends the origin of this clade by at least 10 Myr.

The Berriasian–Valanginian Bajada Colorada Formation of Neuquén Province, Patagonia Argentina, has provided novel information in the last years that helps to elucidate the evolutionary history of different sauropod lineages. The first sauropod taxon recognized from this unit was the diplodocid Leinkupal laticauda. The second taxon is the recently described dicraeosaurid Bajadasaurus pronuspinax.

References:

Pablo Ariel Gallina, Juan Ignacio Canale, & José Luis Carballido (2021).The earliest known titanosaur sauropod dinosaur. Ameghiniana58(1), 35–51 http://dx.doi.org/10.5710/AMGH.20.08.2020.3376

Sander PM, Christian A, Clauss M, et al. Biology of the sauropod dinosaurs: the evolution of gigantism. Biol Rev Camb Philos Soc. 2011;86(1):117-155. doi:10.1111/j.1469-185X.2010.00137.x

Rewriting the Mammoth Family Tree

Mammuthus primigenius, Royal British Columbia Museum. From Wikipedia Commons

From Siberia to Alaska, mammoths were widespread in the northern hemisphere during the Last Ice Age 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. Eventually they dispersed to North America via Beringia, during the Middle Pliocene to Early Pleistocene. Their evolution during the Pleistocene is usually presented as a succession of chronologically overlapping species. M. meridionalis (southern mammoths) arose about 2–1.7 million years ago and was replaced by M. trogontherii (steppe mammoths), which evolved in eastern Asia around 2–1.5 million years ago. Although the relationship among these taxa are uncertain, the prevailing view is that M. columbi (Columbian mammoths) must have arisen from M. trogontheri, which must also be the ancestor of the earliest known examples of M. primigenius (woolly mammoths). A new study by an international team of paleontologists and geneticists offers a glimpse into the origin and evolution of woolly and Columbian mammoth. They used genomic data more than one million years old. So far, the oldest genomic data recovered were from a horse specimen dated to 780–560 thousand years ago.

The researchers recovered genome data from three Early-Middle Pleistocene mammoth molars preserved in Siberian permafrost. The samples were recovered by the late Andrei Sher (Russian Academy of Sciences, Moscow) from the well-documented Olyorian Suite of northeastern Siberia in the 1970s. The first specimen (referred to as ‘Krestovka‘) is morphologically similar to the steppe mammoth (originally defined from the Middle Pleistocene of Europe). It was discovered in 1973 in a cliff exposure along the right side of the Krestovka River. The second specimen (referred to as ‘Adycha’) was recovered in 1976 from a gravel bar in the Adycha River and shows M. trogontherii-like morphology. The third specimen (referred to as ‘Chukochya’) was found in 1971 in a riverbank on the right side of the Bolshaya Chukochya River, and has a morphology consistent with an early form of woolly mammot.

Krestovka specimen showing measurement positions: W = crown width, H = crown height, LL = lamellar length, ET = enamel thickness. From van der Valk et al, 2021

 

Analysis of the DNA suggested that two evolutionary lineages of mammoths inhabited eastern Siberia during the later stages of the Early Pleistocene. One of these lineages is represented by the Krestovka specimen (dated 1.65 Ma), and the second lineage comprises the Adycha specimen (dated 1.3 Ma) along with all Middle and Late Pleistocene woolly mammoths. The results also indicate that the Columbian mammoth is a product of admixture between woolly mammoths and a previously unrecognized ancient mammoth lineage, represented by the Krestovka specimen. This hybridization event took place around 420,000 years ago. The new findings indicate that before the hybridization event North American mammoths belonged to the Krestovka lineage. Previously, a DNA study of the complete mitochondrial genome of Columbian mammoths suggested that interbreeding between late Pleistocene taxa could serve as an indicator of major ecological events, including those surrounding the megafaunal extinctions.

The iconic woolly mammoth evolved into a cold-tolerant, open-habitat specialist through a series of adaptive changes like hair growth, and white and brown fat deposits. The study found that the genes related to these features were present in both the Adycha (87%) and Chukochya (89%) genomes. The findings are suported by the tooth shape of all these northern species that is adapted to grazing   in a cold, open environment.

 

References:

van der Valk, T., Pečnerová, P., Díez-del-Molino, D. et al. Million-year-old DNA sheds light on the genomic history of mammoths. Nature (2021). https://doi.org/10.1038/s41586-021-03224-9

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

Enk, J.; Devault, A.; Widga, C.; Saunders, J.; Szpak, P.; Southon, J.; Rouillard, J. M.; Shapiro, B.; Golding, G. B.; Zazula, G.; Froese, D.; Fisher, D. C.; MacPhee, R. D. E.; Poinar, H. (2016). “Mammuthus population dynamics in Late Pleistocene North America: divergence, phylogeography, and introgression”. Frontiers in Ecology and Evolution. 4. doi:10.3389/fevo.2016.00042.

Enk, J., Devault, A., Debruyne, R. et al. Complete Columbian mammoth mitogenome suggests interbreeding with woolly mammoths. Genome Biol 12, R51 (2011). https://doi.org/10.1186

 

The Middle Eocene Climatic Optimum and the Patagonian floras.

Spore-pollen species from the Eocene of southern South America. From Fernandez et al., 2021

The geological records show that large and rapid global warming events occurred repeatedly during the course of Earth history. Ecological models can predict how biodiversity is affected by those events, but only the fossil record provides empirical evidence about the impact of rising temperatures and atmospheric CO2 on species diversity.

The Middle Eocene Climatic Optimum (MECO, ~40 Ma) was a transient period of global warming that interrupted the general cooling trend initiated at the end of the early Eocene climate optimum (EECO, ~49 Ma). The MECO is related to major oceanographic and climatic changes in the Neo-Tethys and also in other oceanic basins, and lasted about 500–600 Kyr. The MECO altered the pelagic ecosystem with repercussions on the food web structure. The lack of nutrients in the surface waters led to a significant decrease in planktonic foraminiferal accumulation rates, while autotroph nannoplankton accumulation rates remained stable.

Relative frequency of the most common plant groups across the MECO and Late Eocene. From Fernández et al., 2021

The MECO also influenced terrestrial biotas. A new study quantify the response of the floras of southern Patagonia to this warming event. The samples were collected from the Río Turbio Formation in southern Patagonia. The terrestrial palynological assemblage revealed a clear inverse relationship between the abundance of ferns and angiosperms. At the beginning of the MECO, ferns highly increase in abundance (with Cyatheaceae, Dicksoniaceae, and Osmundaceae as the most frequent families), while the abundance of angiosperms decreases dramatically. Podocarpaceae also increases from ~5 % to ~20%. At the core of MECO, ferns drop to a minimum, and angiosperms become dominant. Finally, at the end of the MECO ferns rise again to maximum values and angiosperms decrease.

Palynological analysis also revealed that floras in southern Patagonia were in average ~40% more diverse during the MECO than pre-MECO and post-MECO intervals. The penetration of neotropical migrant species to the highest latitudes along with the persistence of southern Gondwanan natives may have triggered the gradual increasing diversity that can be observed across the MECO.

 

References:

Fernández, D.A., Palazzesi, L., González Estebenet, M.S. et al. Impact of mid Eocene greenhouse warming on America’s southernmost floras. Commun Biol 4, 176 (2021). https://doi.org/10.1038/s42003-021-01701-5

Giorgioni, M., Jovane, L., Rego, E.S. et al. Carbon cycle instability and orbital forcing during the Middle Eocene Climatic Optimum. Sci Rep 9, 9357 (2019). https://doi.org/10.1038/s41598-019-45763-

Sonal Khanolkar, Pratul Kumar Saraswati & Karyne Rogers (2017) Ecology of foraminifera during the middle Eocene climatic optimum in Kutch, India, Geodinamica Acta, 29:2,181-193, DOI: 10.1080/09853111.2017.130084

 

A new giant titanosaur sauropod from the Upper Cretaceous of Argentina

Image credit: Jose Luis Carballido/CTyS-UNLaM/AFP

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. 

Titanosauria is a diverse clade of sauropod dinosaurs represented by nearly 80 genera described worldwide. The group includes the smallest (e.g. Rinconsaurus, and Saltasaurus; with estimated body masses of approximately 6 tonnes) and largest sauropods known to date. The Argentinean record of titanosaurs is particularly abundant with almost 50% of the total world record. For years, Argentinosaurus huinculensis was considered the largest dinosaur that ever walked the Earth. The tittle is now in possession of Patagotitan mayorum, discovered in 2010. The first estimations of Patagotitan body mass suggested that it weigh around 70 tons and reached 40 metres (131 feet) long. But a new study published in 2020 indicates that the body mass of Patagotitan ranges between 42–71 tons, with a mean value of 57 tons.

 

Figure 2. Caudal sequence of MOZ-Pv 1221 and detail of caudal vertebrae 3, 4, 11 and posterior element. From Otero et al., 2021

A new specimen from the Candeleros Formation (98 Ma) of Neuquén Province probably exceeds Patagotitan in size. This new giant titanosaur sauropod was discovered in 2012 and is the second taxon from Candeleros Formation, in addition to Andesaurus. The new specimen, identified as MOZ-Pv 1221, includes a sequence of anterior and middle caudal vertebrae, consisting of the first 20 mostly articulated caudal vertebrae and haemal arches plus isolated posterior caudals, pelvis and other appendicular elements. The preserved caudal sequence corresponds to approximately the anterior half of the tail. The neural spines of the anterior caudal vertebrae in MOZ-Pv 1221 are transversely wider than anteroposteriorly long.

Compared to other giant titanosaurs, the recovered appendicular bones of MOZ-Pv 1221 are larger than any known titanosaur described to date. The maximum dorsoventral height at the proximal section of the scapula is 17% higher than in Patagotitan, 26% higher than in Dreadnoughtus, and 130% higher than in Mendozasaurus. The maximum proximo distal length of the pubis of MOZ-Pv 1221 is 166 cm, which is 10% longer than in Patagotitan, 18% longer than in Dreadnoughtus, and 21% longer than in Futalognkosaurus. Although it is not currently possible to estimate the body mass of MOZ-Pv 1221 because of the fragmentary nature of this specimen, it is clear that this new titanosaur partially recovered from the Candeleros Formation can be considered one of the largest titanosaurs that ever walked the Earth.

 

References:

Otero A, Carballido JL, Salgado L, Canudo JI, Garrido AC (2021), Report of a giant titanosaur sauropod from the Upper Cretaceous of Neuquén Province, Argentina, Cretaceous Research https://doi.org/10.1016/j.cretres.2021.104754

Carballido JL, Pol D, Otero A, Cerda IA, Salgado L, Garrido AC, Ramezani J, Cúneo NR, Krause JM. 2017 A new giant titanosaur sheds light on body mass evolution among sauropod dinosaurs. Proc. R. Soc. B 284: 20171219.
DOI: 10.1098/rspb.2017.1219

Otero, A., J. L. Carballido, A. Pérez Moreno. 2020. The appendicular osteology of Patagotitan mayorum (Dinosauria, Sauropoda). Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2020.1793158

Benson, R. B. J., Campione, N. E., Carrano, M. T., Mannion, P. D., Sullivan, C., Upchurch, P., & Evans, D. C. (2014). Rates of Dinosaur Body Mass Evolution Indicate 170 Million Years of Sustained Ecological Innovation on the Avian Stem Lineage. PLoS Biology, 12(5), http://doi.org/10.1371/journal.pbio.1001853.

Forgotten women of paleontology: Charlotte Murchison

‘The light of science’, a satirical cartoon by Henry T De la Beche, 1832, depicting Charlotte Murchinson

By the early nineteenth century, the study of the Earth became central to the economic and cultural life of Great Britain. 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, although they were still barred from membership in scientific societies. Early female scientists were often born into influential families, like 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.

Charlotte Murchison (neé Hugonin) was born on 18 April 1788 in Hampshire, England. When she met her future husband Roderick Murchison, she was a well-educated woman with great interest in science and he was a cavalry officer in the Dragoons who was more interested in horses and dogs than in Geology. The couple married on August 29, 1815. The  first few years of their marriage they travelled extensively in the Continent. In Italy they became friends with Mary Somerville, the “Queen of Nineteenth Century Science.” In her autobiography, Mary Somerville wrote about Charlotte: “Mrs Murchison was an amiable accomplished woman, drew prettily and what was rare at the time she had studied science, especially geology and it was chiefly owing to her example that her husband turned his mind to those pursuits in which he afterwards obtained such distinction.”

Charlotte (née Hugonin), Lady Murchison by Camille Silvy, albumen print, 1860, NPG Ax50535
© National Portrait Gallery, London

In 1824 the couple moved to London where they began to attend lectures on geology and chemistry. A year later, Roderick Murchison read his first paper to the Geological Society. The same year, the couple explored the southern coast of England. In Lyme Regis, they became friends with Mary Anning, and when Mary visited London in July 1829, she stayed with the Murchisons. In a letter to Charlotte Murchison, dated October 11, 1833, Mary writes about the death of her beloved dog Tray which was killed in a landslide: “I would have answered your kind letter by the return of post, if I had been able. Perhaps you will laugh when I say that the death of my old faithful dog quite upset me, the Cliff fell upon him and killed him in a moment before my eyes, and close to my feet, it was but a moment between me and the same fate”.

In 1826, the couple traveled to the coast of Yorkshire. The fossils collected by Charlote were later described by James de Carle Sowerby in the “Mineral Conchology of Great Britain”. In 1827 Sowerby named an ammonite in her honor: Ammonites murchinsoniae. Willian Buckland also used Charlotte’s collection of fossils to illustrate his “Geology and Mineralogy Considered with References to Natural Theology.”

One of Charlotte Murchison’s illustrations for: Murchison, Roderick Impey. The Silurian system (Image: archive.org)

In 1828, Charlotte and her husband joined Charles Lyell on a long journey around Europe. In his notes Charles Lyell praised the active participation of Charlotte: “Mrs . M. is very diligent , sketching, labelling specimens & making out shells in which last she is an invaluable assistant.” Nevertheless, in the summer of 1832, Lyell refused to let women attend his lectures in Geology at Kings College London because he thought that women in a classroom would be “unacademical”. Charlotte and Mary Somerville were among the women who insisted on being allowed to attend the lectures. Some days later, in a letter to his long time friend William Whewell, Mary Somerville wrote: ‘It is decided by the Council of the University that ladies are to be admitted to the whole course, so you can see what in[va]sions we are making on the laws of learned societies, reform is nothing to it”

It was suggested that Lyell’s capitulation was related to Charlotte’s presence among the crowd. In 1834, William Whewell welcomed scientific women to the third meeting of the British Association. In an invitation addressed to Mary Somerville, he wrote: “I expect Mrs. Buckland and Mrs. Murchinson and several other ladies…”

Charlotte continued sketching the cliffs and collecting fossils but due to her health issues, she was not abble to join her husband in many of his late travels. By the 1860s Charlotte’s health has deteriorated. She died on 9 February 1869 at her home in Belgrave Square, London.

 

References:

Kölbl-Ebert, Martina (1997). “Charlotte Murchison (Née Hugonin) 1788-1869”. Earth Sciences History (History of Earth Sciences Society) 16 (1): 39–43 https://doi.org/10.17704/eshi.16.1.97014235w8u4k414

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

EYLES, V. A. (1971). Roderick Murchison, Geologist and Promoter of Science. Nature, 234(5329), 387–389. doi:10.1038/234387a0

Halloween special VIII: The Great Dying

“Out of the Aeons” is a short story by H. P. Lovecraft and Hazel Heald. The story introduces the powerful Ghatanothoa, a Great Old One and the first-born of Cthulhu, brought to Earth from the planet Yuggoth by the Mi-go, an anciente alien race, who built a colossal fortress atop the Mount Yaddith-Gho, and sealed Ghatanothoa inside the mountain. Those who worship this entity hold the god responsible for earthquaques and other natural disasters. Like Groth himself, Ghatanothoa is the harbinger of death.

The fossil record indicates that more than 95% of all species that ever lived are now extinct. Occasionally, extinction events reach a global scale with many species of all ecological types dying out in a near geological instant. These mass extinctions were originally identified in the marine fossil record and have been interpreted as a result of catastrophic events or major environmental changes that occurred too rapidly for organisms to adapt.

Global paleogeographic map for the Permian-Triassic transition showing the location of the Siberian Traps Large Igneous Province. From Vajda et al., 2019

During the last 540 million years five mass extinction events shaped the history of the Earth. The end-Permian extinction (PTB) is the most severe biotic crisis in the fossil record, with as much as 95% of the marine animal species and a similarly high proportion of terrestrial plants and animals going extinct . This great crisis occurred 252 million years ago (Ma), and is linked to the emplacement of the large igneous province of the Siberian Traps. A new study published early this month in the journal Nature Geoscience is the first to conclusively reconstruct the entire cascade of events that lead to the PTB mass extinction.

The team lead by Hana Jurikova used the boron isotope of well preserved shells of brachiopods and paired with carbon and oxygen isotope data, generating a new record of ocean pH for the Permian/Triassic boundary. These findings indicate that the PTB mass extinction was triggered by a multimillennial-scale voluminous injection of carbon to the atmosphere by the emplacement of Siberian Traps sill intrusions. Massive volcanic eruptions with lava flows, released large quantities of sulphur dioxide, carbon dioxide, thermogenic methane and large amounts of HF, HCl, halocarbons and toxic aromatics and heavy metals into the atmosphere. The CO2 greenhouse effect resulted in strong heating and acidification of the surface ocean, which prompted the initial disappearance of all reef-building taxa. Acid rain likely had an impact on freshwater ecosystems and may have triggered forest dieback. 

 

References:

Hana Jurikova et al, Permian–Triassic mass extinction pulses driven by major marine carbon cycle perturbations, Nature Geoscience (2020). DOI: 10.1038/s41561-020-00646-4

V. Vajda et al. (2020), End-Permian (252Mya) deforestation, wildfires and flooding—An ancient biotic crisis with lessons for the present, Earth and Planetary Science Letters 529 (2020) 115875 https://doi.org/10.1016/j.epsl.2019.115875

H. P. Lovecraft & Hazel Heald, “Out of the Aeons”, Weird Tales magazine, 1935