Introducing Dynamoterror dynastes, the powerful terror ruler.

Frontals of Dynamoterror dynastes in rostral view. From McDonald et al., 2018. (Scale bars = 5 cm)

Tyrannosauroidea is a relatively derived group of theropod dinosaurs more closely related to birds than to other large theropods such as allosauroids and spinosaurids. The clade originated in the Middle Jurassic, approximately 165 million years ago, and for most of their evolutionary history, tyrannosauroids were mostly small-bodied animals that only reached gigantic size during the final 20 million years of the Cretaceous. Until recently, all tyrannosaurs fossils were limited to Asia and North America, but the latest discoveries suggest a more cosmopolitan distribution during their early evolution.

All tyrannosaurs were bipedal predators characterized by premaxillary teeth with a D-shaped cross section, fused nasals, extreme pneumaticity in the skull roof and lower jaws, a pronounced muscle attachment ridge on the ilium, and an elevated femoral head. The clade was a dominant component of the dinosaur faunas of the American West shortly after the emplacement of the Western Interior Seaway (about 99.5 Mya).

Paleogeography of North America during the late Campanian Stage of the Late Cretaceous (∼75 Ma). From Sampson et al., 2010

Dynamoterror dynastes, the most recent taxon described from the lower Campanian of northwestern New Mexico, provides additional data on the morphology and diversity of early tyrannosaurines in Laramidia. The new specimen lived during the Late Cretaceous period, approximately 78 million years ago. The name derived from Greek word dynamis (“power”) and the Latin word terror. The specific name is a Latin word meaning “ruler. Dynamoterror was collected in San Juan County, New Mexico, and is the first associated tyrannosaurid skeleton reported from the Menefee Formation.

The holotype (UMNH VP 28348) is an incomplete associated skeleton including the left and right frontals, four fragmentary vertebral centra, fragments of dorsal ribs, right metacarpal II, supraacetabular crest of the right ilium, unidentifiable fragments of long bones, phalanx 2 of left pedal digit IV, and phalanx 4 of left pedal digit IV. The right and left frontals both are incomplete; the dimensions of the right frontal are similar to a subadult specimen of Tyrannosaurus rex, suggesting that UMNH VP 28348 represents a subadult or adult individual. The reconstructed skull roof of Dynamoterror present several tyrannosaurine features, such as large supratemporal fossae and a tall sagittal crest on the frontals, providing an expanded attachment area for enormous jaw-closing muscles.

 

References:

McDonald AT, Wolfe DG, Dooley AC Jr. (2018) A new tyrannosaurid (Dinosauria: Theropoda) from the Upper Cretaceous Menefee Formation of New Mexico. PeerJ 6:e5749 https://doi.org/10.7717/peerj.5749

Brusatte SL, Norell MA, Carr TD, Erickson GM, Hutchinson JR, et al. (2010) Tyrannosaur paleobiology: new research on ancient exemplar organisms. Science 329: 1481–1485. doi: 10.1126/science.1193304

Sampson SD, Loewen MA, Farke AA, Roberts EM, Forster CA, Smith JA, et al. (2010) New Horned Dinosaurs from Utah Provide Evidence for Intracontinental Dinosaur Endemism. PLoS ONE 5(9): e12292. https://doi.org/10.1371/journal.pone.0012292

 

 

 

 

 

 

 

 

 

 

 

 

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Forgotten women of paleontology: Irene Crespin

Irene Crespin (1896-1980)

Irene Crespin was born on November 12, 1896, in Kew, Victoria, Australia. In her memories, she wrote that her interest in Palaeontology began early in her life, when she was one of the first students to attend the Mansfield High School in northeastern Victoria. The head master of for a short period was the eminent Australian geologist Charles Fenner.

In 1919, she graduated with a B.A. from the University of Melbourne. In 1927 she joined the Commonwealth Government as Assistant Palaeontologist to Frederick Chapman at the National Museum of Victoria. Chapman was an authority on Foraminifera and was president of the Royal Society of Victoria. About her time at the Museum she wrote: “In the early days, we passed through the depression era. Our salaries were reduced overnight. I was reduced to six pounds a week. They were difficult times for us all. One would walk a long distance to save a threepenny tram fare.”

Dr Irene Crespin with W. Baragwanath, Secretary of Mines for Victoria, probably visiting a Cooksonia plant site, c. 1927 (From Turner 2007)

In 1936, Crespin succeeded Chapman as Commonwealth Palaeontologist. On February 10th, she was transferred from the National Museum, Melbourne to join the Commonwealth Geological Adviser, Dr. W.G. Woolnough, in Canberra. About her new position she wrote: “Of course, being a woman, and despite the tremendous responsibility placed upon me with the transfer to Canberra, I was given a salary of about half of that which Chapman received. Later the Chairman of the Public Service Board told me that I was being put on trial.”

She becoming greatly interested in the Tertiary microfaunas, and for some time she was the only professional micropaleontologist on the Australian mainland. Her research took her all over Australia. In 1939, she received permission from the Minister of the Interior to visit Java and Sumatra to discuss the problems of Tertiary correlation in the Netherlands East Indies with Papua and New Guinea.

Crespin’s photo of her aeroplane and crew on an overseas trip to Java, Indonesia, 1939 (From Turner 2007)

Crespin was well respected internationally and was a regular participant in national and international scientific conferences. In 1953, many of her books and specimens were destroyed as a result of a fire in the Canberra offices. The same year, she received Queen Elizabeth II’s coronation medal. In 1957 she was president of the Royal Society of Canberra, and was awarded with the Clarke medal of the Royal Society of New South Wales.

During her career she published 86 papers as sole author and more 22 in collaboration with other scientists. She was made an honorary fellow of the Royal Microscopical Society, London, in 1960. She became an honorary member of the Australian and New Zealand Association for the Advancement of Science in 1973. She died in Canberra, on January 2, 1980.

References:

Turner, S. (2007). Invincible but mostly invisible: Australian women’s contribution to geology and palaeontology. Geological Society, London, Special Publications, 281(1), 165–202. doi: 10.1144/sp281.11

Crespin, Irene (1975). “Ramblings of a micropalaeontologist”. BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS.

 

Introducing Jinguofortis perplexus.

Photograph of main slab of J. perplexus (Credit: Wang et al., 2018)

Birds originated from a theropod lineage more than 150 million years ago. By the Early Cretaceous, they diversified, evolving into a number of groups of varying anatomy and ecology. 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. Most of these fossils are from the Jehol Biota of northeastern China, dated between approximately 130.7 and 120 million years ago. The Jehol Biota provides an incredibly detailed picture of early birds, including Jeholornis, slightly more derived than Archaeopteryx, that lived with Sapeornis, Confuciusornis, and the earliest members of Enantiornithes and Ornithuromorpha. The clade Ornithothoraces (characterized by a keeled sternum, elongate coracoid, narrow furcula, and reduced hand) along with Jeholornithiformes, Confuciusornithiformes and Sapeornithiformes, form the clade Pygostylia. Basal members of this clade are essential to understand the evolution of the modern avian bauplan. The trait that gives the group its name is the presence of a pygostyle, a set of fused vertebrae at the end of the tail.

Jinguofortis perplexus gen. et sp. nov., from the Early Cretaceous of China, exhibits a mosaic combination of plesiomorphic nonavian theropod features like a fused scapulocoracoid and more derived traits, including the earliest evidence of reduction in manual digits among birds. The generic name is derived from “jinguo” (Mandarin), referring to female warrior, and “fortis” for brave (Latin). The specific name is derived from Latin “perplexus,” and highlights the combination of plesiomorphic and derived features present in the holotype specimen.

Holotype of J. perplexus. (Scale bar, 5 cm.) From Wang et al., 2018.

The holotype (IVPP V24194) was collected near the village of Shixia, Hebei Province, China. Biostratigraphic correlation confirms that the fossil-bearing horizon belongs to the Lower Cretaceous Dabeigou Formation of the Jehol Biota (127 ± 1.1 Ma). The holotype of Jinguofortis is subadult or adult given the bone histology, the presence of a fused carpometacarpus, tarsometatarsus, and pygostyle. The body mass estimated is 250.2 g, the wing span is 69.7 cm, with a wing area of 730 cm2.

Jinguofortis exhibits the following features: dentary with at least six closely packed teeth; scapula and coracoid fused into a scapulocoracoid in the adult; sternum ossified; deltopectoral crest of humerus large and not perforated; minor metacarpal strongly bowed caudally; minor digit reduced with manual phalangeal formula of 2–3-2; metatarsals III and IV subequal in distal extent; pedal phalanx II-2 with prominent heel proximally; and forelimb 1.15 times longer than hindlimb. The highly vascularized fibro-lamellar bone tissue indicates that Jinguofortis grew rapidly in early development, but the growth rate had slowed substantially by the time of death. The histology of Jinguofortis is comparable to that of Chongmingia and Confuciusornis, suggesting a similar growth pattern shared among these basal pygostylians. The phylogenetic analysis recovered Jinguofortis as the sister to Chongmingia. The clade uniting these two specimens is Jinguofortisidae, and constitutes the second most basal pygostylian lineage.

Forelimb of Jinguofortis. (A) Photograph. (B) Line drawing. (Scale bar, 1 cm.) From Wang et al., 2018.

Early avian flight clearly underwent a series of evolutionary experiments, as demonstrated by the diverse combination of plesiomorphic and derived features found among early extinct birds. The most striking primitive feature present in the flight apparatus of Jinguofortis is the fused scapulocoracoid, present predominantly in nonavian theropods. The convergently evolved scapulocoracoid in jinguornithids and confuciusornithiforms suggests that these basal clades likely reacquired a similar level of osteogenesis (or gene expression) present in their nonavian theropod ancestors.

 

References:

Wang, M., Stidham, T. A., & Zhou, Z. (2018). A new clade of basal Early Cretaceous pygostylian birds and developmental plasticity of the avian shoulder girdle. Proceedings of the National Academy of Sciences, 201812176. doi:10.1073/pnas.1812176115

The Tyrannosauroids from the Southern Hemisphere.

Santanaraptor lived in South America during the Early Cretaceous about 112 million years ago (From Wikimedia Commons).

Tyrannosauroidea, the superfamily of carnivorous dinosaurs that includes the iconic Tyrannosaurus rex, was mainly distributed in the Northern Hemisphere. However, a few specimens from Australia (Timimus hermani and the articulated pubes NMV P186046) and Brazil (Santanaraptor placidus), have been referred to this clade.

Santanaraptor was unearthed in 1996 in the Romualdo Group (Santana Formation). The holotype is a juvenile partial skeleton that may have reached 1.25 metres (4.1 ft) in length, and it was presumed to be similar to Dilong and Guanlong. It was first described as a coelurosaurian theropod by Alexander Kellner in 1999, but in 2014 Thomas Holtz classified Santanaraptor as the first tyrannosauroid known from Gondwana. Delcourt and Grillo (2018), also placed Santanaraptor within Tyrannosauroidea based on the following features: the absence of an accessory ridge on the lateral surface of the cnemial crest; the absence of a horizontal groove across the astragalar condyles anteriorly; a deep fossa on the medial surface of the femoral head, lateral to the trochanteric fossa; an ischial medial apron positioned along the anterior margin of its shaft in medial view; the lesser trochanter and the greater trochanter extending to approximately the same level proximally; the proximal margin of the femur is concave in posterior view due to a greater trochanter that is elevated substantially relative to the lateral portion of the proximal surface of the head; and a shallow femoral extensor groove on the anterior surface of the distal end that is expressed as a broad concave anterior margin in distal view but present as an extensive depression on the anterior surface of the femur.

Holotypic left femur of Timimus hermani (From Wikimedia Commons)

Timimus was unearthed in 1994 from Eumeralla Formation and shares similar features with Tyrannosauroidea, but due to the incompleteness of the Timimus holotype, is difficult to properly evaluate its phylogenetic position. The same applies to NMV P186046. It was suggested (Benson et al., 2012) that NMV P186046 and the Timimus holotype may represent a single taxon given their similar phylogenetic positions and congruent sizes, although they did not come from the same site.

Time-calibrated phylogeny of Tyrannosauroidea. From Delcourt and Grillo, 2018.

Tyrannosauroidea had a Eurasian distribution, but basal lineages of the newly proposed clade, Pantyrannosauria (the most inclusive clade, containing Tyrannosaurus rex and Dilong paradoxus, but not Proceratosaurus bradleyi), were distributed across Europe (Juratyrant, Eotyrannus and Aviatyrannis), North America (Stokesosaurus), South America (Santanaraptor), Australia (Timimus), and Asia (Dilong and Xiongguanlong). It was hypothesized that all basal lineages of Pantyrannosauria were already established in the Late Jurassic before the complete separation of Gondwana and Laurasia.

The fact that Santanaraptor and Timimus were relatively small suggests that Gondwanan tyrannosauroids remained small in comparison to northern species. The presence of Santanaraptor in a semi-arid environment with marine incursion also suggests that tyrannosauroids were not only found in humid paleoenvironments.

References:

Rafael Delcourt, Orlando Nelson Grillo , Tyrannosauroids from the Southern Hemisphere: Implications for biogeography, evolution, and taxonomy. Palaeo (2018), doi: 10.1016/j.palaeo.2018.09.003

Apesteguía, S., Smith, N.D., Juárez Valieri, R., Makovicky, P.J., 2016. An Unusual New Theropod with a Didactyl Manus from the Upper Cretaceous of Patagonia, Argentina. PLoS One 11, 1–41. doi:10.1371/journal.pone.0157793

Benson, R.B.J., Rich, T.H., Vickers-Rich, P., Hall, M., 2012. Theropod fauna from southern Australia indicates high polar diversity and climate-driven dinosaur provinciality. PLoS One 7, e37122. doi:10.1371/journal.pone.0037122

Porfiri, J. D., Novas, F. E., Calvo, J. O., Agnolín, F. L., Ezcurra, M. D. & Cerda, I. A. 2014. Juvenile specimen of Megaraptor (Dinosauria, Theropoda) sheds light about tyrannosauroid radiation. Cretaceous Research 51: 35-55. https://doi.org/10.1016/j.cretres.2014.04.007

Holtz Jr, T.R., 2004. Tyrannosauroidea, in: Weishampel, D.B., Dodson, P., Osm (Eds.), The Dinosauria. University of California Press, Berkeley, pp. 111–136.

On This Side of Paradise.

Stardate 3417.3. The Enterprise has arrived to the planet Omicron Ceti III to catalog the destruction suffered by an agricultural colony stablished in 2264. It was assumed that the colonists are dead because the planet was bathed in Berthold rays, a lethal form of radiation. Although there was no sign of animal life on the planet, the colonists were found alive and in excellent health. Mr. Spock, intrigued about the survival of the colony, is conducted by Leila Kalomi, a botanist he had met six years prior on Earth, to a field with very strange flowers which expelled some spores into his face. Spock begun to feel sick, and after a brief agonizing struggle, he smiled and confessed his love for Leila. Like Spock, all the members of the Enterprise that were exposed to the spores changed their behavior. The only one who resisted the effect of the spores was Captain Kirk.

Spock with Leila Kalomi (Image: CBS)

The key elements for the colony survival were the spores. The term ‘spores’ derived from the Greek word for seed. In a broad sense, spores are the reproductive structures of bacteria, fungi, algae, protists and land plants, adapted for dispersion and surviving for extended periods of time during unfavorable conditions.

The colonization of land by vascular plants in the Paleozoic was one of the most significant events in Earth’s history. We could hypothesize that terrestrial colonization was not possible prior to the evolution of the sporopollenin spore wall, and this adaptation is considered to be a synapomorphy of the embryophytes. Sporopollenin is the major component of the spore (and pollen) wall. This highly resistant biopolymer occurs in certain charophyceans, but is located in an inner layer of the zygote wall.

Cryptospores from the Early Middle Ordovician of Argentina (From Rubinstein et al., 2010)

Like their algal ancestors, all plant life cycle goes through both haploid (gametophyte) and diploid (sporophyte) stages. In vascular plants, the sporophyte generation predominates. The sporophyte produces the spores, which contain only a single copy of the chromosomes. The earliest dispersed spores attributable to terrestrial plants, termed cryptospores, are known from the Middle Ordovician. Cryptospores are believed to have been produced by bryophyte-like plants, but recently, they were interpreted as the product of a diverse group of mostly extinct plants, whose precise affinities to living clades remain unclear.

C. barrandei sp. nov., from Czech Republic (scale bar, 10 mm). From Libertín et al., 2018.

The description of Cooksonia barrandei (432 my, Czech Republic) shed light on the origins of the alternation of generations in land plants. The genus Cooksonia (named in honor of Isabel Cookson) is generally accepted as the oldest land plant, with a broad distribution in the Late Silurian and Early Devonian periods, including North America, North Africa, Europe, Asia and South America. Cooksonia barrandei (the species name is honoring Joachim Barrande, a famous French palaeontologist who lived in Prague), and is five million years older than the oldest previously described cooksonioids (427 mya). The plants were isosporous (produced only one kind of spore) and of small size, with a bent, isotomously branched axis with terminal branches completely preserved.

Star Trek has been a cult phenomenon for decades. The Original Series premiered on September 8, 1966, and has spawned five successor shows starting in the 1980s and several feature films , comic books, novels and an animated series. Star Trek also influenced generations of viewers about advanced science and engineering. “This side of Paradise” remains as one of the best episode of Star Trek. It was premiered on March 2, 1967. The title was taken by the final line of the poem “Tiare Tahiti” by Rupert Brooke: “Well this side of Paradise! …. There’s little comfort in the wise.”

References:

Libertín, Milan; Kvaček, Jiří; Bek, Jiří; Žárský, Viktor & Štorch, Petr (2018), “Sporophytes of polysporangiate land plants from the early Silurian period may have been photosynthetically autonomous”, Nature Plants, 4 (5): 269–271, doi:10.1038/s41477-018-0140-y

Rubinstein, C. V., Gerrienne, P., de la Puente, G. S., Astini, R. A., & Steemans, P. (2010). Early Middle Ordovician evidence for land plants in Argentina (eastern Gondwana). New Phytologist, 188(2), 365–369. doi:10.1111/j.1469-8137.2010.03433.x 

 

A very short history of Dinosaurs.

Evolutionary relationships of dinosaurs. From Benton 2018.

On 20 February 1824, William Buckland published the first report of a large carnivore animal: the Megalosaurus. The description was based on specimens in the Ashmolean Museum, in the collection of Gideon Algernon Mantell of Lewes in Sussex, and a sacrum donated by Henry Warburton (1784–1858). One year later, the Iguanodon entered in the books of History followed by the description of Hylaeosaurus in 1833. After examined the anatomy of these three genera, Richard Owen erected the clade Dinosauria in 1842.

Dinosaurs likely originated in the Early to Middle Triassic. The closest evolutionary relatives of dinosaurs include flying pterosaurs and herbivorous silesaurids. Early ecological divergences in dinosaur evolution are signaled by disparity in dental morphology, which indicates carnivory in early theropods, herbivory in ornithischians, and omnivory in sauropodomorph (subsequently sauropodomorphs underwent a transition to herbivory).

Eoraptor lunensis, outcropping from the soil. Valle de la Luna (Moon Valley), Parque Provincial Ischigualasto, Provincia de San Juan, Argentina.

The oldest dinosaurs remains are from the late Carnian (230 Ma) of the lower Ischigualasto Formation in northwestern Argentina. Similarly, the Santa Maria and Caturrita formations in southern Brazil preserve basal dinosauromorphs, basal saurischians, and early sauropodomorphs. In North America, the oldest dated occurrences of vertebrate assemblages with dinosaurs are from the Chinle Formation. Two further early dinosaur-bearing formations, are the lower (and upper) Maleri Formation of India and the Pebbly Arkose Formation of Zimbabwe. These skeletal records of early dinosaurs document a time when they were not numerically abundant, and they were still of modest size.

During the Late Triassic period numerous extinctions, diversifications and faunal radiations changed the ecosystems dynamics throughout the world. Nevertheless, dinosaurs exhibited high rates of survival. According to the competitive model, the success of dinosaurs was explained in terms of their upright posture, predatory skills, or warm-bloodedness. In the opportunistic model, dinosaurs emerged in the late Carnian or early Norian, and then diversified explosively. The current model contains some aspects of both the classic competition model and the opportunistic model. In this model, the crurotarsan-dominated faunas were replaced by a gradual process probably accelerated by the ecological perturbation of the CPE (Carnian Pluvial Episode).

Ingentia prima outcropping from the soil.

In the Jurassic and Cretaceous dinosaurs achieved enormous disparity. Sauropodomorphs achieved a worldwide distribution and become more graviportal and increased their body size. Gigantism in this group has been proposed as the result of a complex interplay of anatomical, physiological and reproductive intrinsic traits. For example, the upright position of the limbs has been highlighted as a major feature of the sauropodomorph bauplan considered an adaptation to gigantism. However, the discovery of Ingentia prima, from the Late Triassic of Argentina, indicates that this feature was not strictly necessary for the acquisition of gigantic body size.

Ornithischian were primitively bipedal, but reverted to quadrupedality on at least three occasions: in Ceratopsia, Thyreophora and Hadrosauriformes. The presence of early armored dinosaurs (thyreophorans) in North America, Asia, and Europe, but their absent from the southern African record, suggests some degree of provinciality in early ornithischian faunas.

Archaeopteryx lithographica, specimen displayed at the Museum für Naturkunde in Berlin. (From Wikimedia Commons)

Theropod dinosaurs also increased their diversity and exhibit a greater range of morphological disparity. The group underwent multiple parallel increases in brain size. The volumetric expansion of the avian endocranium began relatively early in theropod evolution. For instance, the endocranium of Archaeopteryx lithographica is volumetrically intermediate between those of more basal theropods and crown birds. The digital brain cast of Archaeopteryx also present an indentation that could be from the wulst, a neurological structure present in living birds used in information processing and motor control with two primary inputs: somatosensory and visual. The extensive skeletal pneumaticity in theropods such as Majungasaurus demonstrates that a complex air-sac system and birdlike respiration evolved in birds’ theropod ancestors. Anatomical features like aspects of egg shape, ornamentation, microstructure, and porosity of living birds trace their origin to the maniraptoran theropods, such as oviraptorosaurs and troodontids. In addition, some preserving brooding postures, are known for four oviraptorosaurs, two troodontids, a dromaeosaur, and one basal bird providing clear evidence for parental care of eggs.

Nonavian dinosaurs disappeared more or less abruptly at the end of the Cretaceous (66 mya). Birds, the only living dinosaurs, with more than 10,500 living species are the most species-rich class of tetrapod vertebrates.

 

References:

Benson, R. B. J. (2018). Dinosaur Macroevolution and Macroecology. Annual Review of Ecology, Evolution, and Systematics, 49(1).  doi:10.1146/annurev-ecolsys-110617-062231

Michael J. Benton et al. The Carnian Pluvial Episode and the origin of dinosaurs, Journal of the Geological Society (2018). DOI: 10.1144/jgs2018-049

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.

 

Introducing Caelestiventus hanseni.

A 3D printed model of Caelestiventus skull.

Pterosaurs were the first flying vertebrates appearing initially in Late Triassic. The group achieved high levels of morphologic and taxonomic diversity during the Mesozoic, with more than 200 species recognized so far. 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. Because of the fragile nature of their skeletons the fossil record of pterosaurs is strongly biased towards marine and lacustrine depositional environments. Therefore, Triassic pterosaurs are extraordinarily rare and consists of fewer than 30 specimens, including single bones. With the single exception of Arcticodactylus cromptonellus from fluvial deposits in Greenland, the other specimens are known from marine strata in the Alps.

Pterosaurs have 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.

a, Schematic silhouette of a dimorphodontid pterosaur in dorsal view. b, Preserved skull and mandible elements of C. hanseni. From Brooks B. Britt et al., 2018.

Caelestiventus hanseni, from the Upper Triassic of North America, is the oldest pterosaur ever discovered, and it predates all known desert pterosaurs by more than 65 million years. The generic name comes from the Latin language: caelestis, ‘heavenly or divine’, and ventus, ‘wind’. The species name, ‘hanseni’, honors Robin L. Hansen, a geologist, who facilitated work at the Saints & Sinners Quarry.

The holotype, BYU 20707, includes the left maxilla fused with the jugal, the right maxilla, the right nasal, the fused frontoparietals, the right and left mandibular rami, the right terminal wing phalanx and three fragments of indeterminate bones. The maxilla, jugal, frontoparietal, and mandibular rami of the specimen are pneumatic. The unfused skull and mandibular elements suggest that BYU 20707 was skeletally immature or had indeterminate growth. Based on the relationship between the length of the terminal wing phalanges and wing span in other non-pterodactyloid pterosaurs the new taxon would have a wing span greater than 1.5 m.

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

Caelestiventus hanseni is placed as sister taxon to Dimorphodon macronyx. Both share the following derived features: a ventral blade along the dentary that forms a rostral keel and becomes a flange distally; a diastema between the second large mandibular tooth and the following smaller teeth; the overall morphology of the maxilla; the shape of the external naris and antorbital fenestra; the external naris by far the largest skull opening; the orbit smaller than the antorbital fenestra; and teeth with bicuspid apices. But despite their morphological similarity, C. hanseni and D. macronyx lived in very different environments. Dimorphodon, discovered by Mary Anning, was an island dweller in a humid climate and was preserved in the marine Blue Lias of southern England.

The significance of C. hanseni lies in its exceptional state of preservation, and its close phylogenetic relationship with Dimorphodon macronyx, indicating that dimorphodontids originated by the Late Triassic and survived the end-Triassic extinction event.

 

References:

Brooks B. Britt et al. Caelestiventus hanseni gen. et sp. nov. extends the desert-dwelling pterosaur record back 65 million years, Nature Ecology & Evolution (2018). DOI: 10.1038/s41559-018-0627-y

Learning from Past Climate Changes

In the last 540 million years, five mass extinction events shaped the history of the Earth. Those events were related to extreme climatic changes and were mainly caused by asteroid impacts, massive volcanic eruption, or the combination of both.  On a global scale the main forces behind climatic change are: solar forcing, atmospheric composition, plate tectonics, Earth’s biota, and of course, us. Human activity is a major driver of the dynamics of Earth system. From hunter-gatherer and agricultural communities to the highly technological societies of the 21st century, humans have driven the climate Earth system towards new, hotter climatic conditions. Until the Industrial Revolution, the average global CO2 levels fluctuated between about 170 ppm and 280 ppm. But with the beginning of the Industrial Era, that number risen above 300 ppm, currently averaging an increase of more than 2 ppm per year. The average monthly level of CO2 in the atmosphere in last April exceeded the 410 ppm for first time in history. Thus we could hit an average of 500 ppm within the next 45 years, a number that has been unprecedented for the past 50–100+ million years according to fossil plant-based CO2 estimates. This current human-driven change far exceed the rates of change driven by geophysical or biosphere forces that have altered the Earth System trajectory in the past, and it poses severe risks for health, economies and political stability. Learning from past climatic changes is critical to our future.

Planktonic foraminifera from the Sargasso Sea in the North Atlantic Ocean. (Photograph courtesy Colomban de Vargas, EPPO/SBRoscoff.)

Microfossils from deep-sea are crucial elements for the understanding of our past and present oceans. Their skeletons take up chemical signals from the sea water, in particular isotopes of oxygen and carbon. Over millions of years, these skeletons accumulate in the deep ocean to become a major component of biogenic deep-sea sediments. The importance of microfossils as tool for paleoclimate reconstruction was recognized early in the history of 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.

Diatoms and radiolarians are susceptible to different set of dissolution parameters than calcareous fossils, resulting in a different distribution pattern at the sea floor and have been used for temperature estimates in the Pacific and in the Antarctic Oceans, especially where calcareous fossils are less abundant. Diatom assemblages are also used in reconstructions of paleoproductivity.

Scanning electron microscope image of different types of pollen grains. Image from Wikipedia.

Pollen and other palynomorphs proved to be an extraordinary tool to paleoenvironmental reconstruction too. Pollen analysis involves the quantitative examination of spores and pollen at successive horizons through a core, specially in lake, marsh or delta sediments, especially in Quaternary sediments where the parent plants are well known. This provide information on regional changes in vegetation through time, and it’s also a valuable tool for archaeologists because it gives clues about man’s early environment and his effect upon it.

Stomatal frequency of land plants, which has been shown in some species to vary inversely with atmospheric pCO2, has been used to estimate paleo-pCO2 for multiple geological time periods. Stomata are the controlled pores through which plants exchange gases with their environments, and play a key role in regulating the balance between photosynthetic productivity and water loss through transpiration.

Temple I on The Great Plaza and North Acropolis seen from Temple II in Tikal, Guatemala. From Wikimedia Commons

Paleoecological records indicate that the transition to agriculture was a fundamental turning point in the environmental history of Mesoamerica. Tropical forests were reduced by agricultural expansion associated with growing human populations. Also soil loss associated with deforestation and erosion was one of the most consequential environmental impacts associated with population expansion in the Maya lowlands. This environmental crisis ended with the collapse of the Classic Maya society.

Human activity has significantly altered the climate in less than a century. Since 1970 the global average temperature has been rising at a rate of 1.7°C per century, and the rise in global CO2 concentration since 2000 is 10 times faster than any sustained rise in CO2 during the past 800,000 years. Today the most politically unstable countries are also places where environmental degradation affected food production and water supply. Other human societies have succumbed to climate change – like the Akkadians – while others have survived by changing their behavior in response to environmental change. We have the opportunity to protect the future of our own society by learning from the mistakes of our ancestors.

References:

David Evans, Navjit Sagoo, Willem Renema, Laura J. Cotton, Wolfgang Müller, Jonathan A. Todd, Pratul Kumar Saraswati, Peter Stassen, Martin Ziegler, Paul N. Pearson, Paul J. Valdes, Hagit P. Affek. Eocene greenhouse climate revealed by coupled clumped isotope-Mg/Ca thermometry. Proceedings of the National Academy of Sciences, 2018; 201714744 DOI: 10.1073/pnas.1714744115

Nicholas P. Evans et al., Quantification of drought during the collapse of the classic Maya civilization, Science (2018); DOI: 10.1126/science.aas9871 

Will Steffen, et al.; Trajectories of the Earth System in the Anthropocene; PNAS (2018) DOI: 10.1073/pnas.1810141115

Lingwulong shenqi, the “Amazing Dragon”, and the dispersal of Sauropods.

Skeletal reconstruction and exemplar skeletal remains of Lingwulong shenqi. Scale bars = 100 cm for a and 5 cm for b–o. From Xu et al., 2018

Sauropods were the largest terrestrial vertebrates. Their morphology is easy recognizable: a long, slender neck and a tail at the end of a large body supported by four columnar limbs. Sauropods dominated many Jurassic and Cretaceous terrestrial faunas. Although they were globally distributed, the absence of Diplodocoidea from East Asia has been interpreted as a biogeographic pattern caused by the Mesozoic fragmentation of Pangea. However, a newly discovered dinosaur from the Middle Jurassic of northern China suggests that Sauropods dispersed and diversified earlier than previously thought.

Lingwulong shenqi — literally the “amazing dragon from Lingwu” — is the first well-preserved confirmed diplodocoid from East Asia (23 synapomorphies support the placement of Lingwulong within Diplodocoidea with 10 of these being unequivocal). The holotype, (LM) V001a, is a partial skull comprising the braincase, skull roof, and occiput, and an associated set of dentary teeth. The paratype, (LGP) V001b, comprises a semi-articulated partial skeleton including a series of posterior dorsal vertebrae, complete sacrum, the first caudal vertebra, partial pelvis, and incomplete right hind limb.

An artist’s interpretation of what Lingwulong shenqi (Image: Zhang Zongda)

The Lingwulong specimens were found in the Yanan Formation at Ciyaopu, in northwest China. This formation has been divided in four or five members. Although, no radiometric constraints have been obtained for the Yanan Formation, its age has been estimated on the basis of biostratigraphy. The presence of a conchostracans assemblage (including Palaeoleptoestheria, Triglypta, and Euestheria) is indicative of a Middle Jurassic age.

The East Asian Isolation Hypothesis (EAIH) has become a well-established explanation of profound differences between Jurassic (and sometimes Early Cretaceous) Asian terrestrial faunas, that resulted in the evolution of endemic groups such as mamenchisaurid sauropods, and the early diverging lineage of tetanurans, oviraptorosaurs, therizinosaurs. In this model, the isolation ended in the Early Cretaceous when marine regressions allowed the invasion of groups from elsewhere in Pangaea, and the dispersal of Asian endemics (e.g., oviraptorosaurs, marginocephalians) into Europe and North America. However, it was claimed that diplodocoids never took part in these dispersals because the end-Jurassic extinction that greatly reduced their diversity and geographic range in the Early Cretaceous. The discovery of Lingwulong undermines the EAIH, forcing a significant revision of hypotheses concerning the origins and early radiation of Neosauropoda.

 

References:

Xing Xu, Paul Upchurch, Philip D. Mannion, Paul M. Barrett, Omar R. Regalado-Fernandez, Jinyou Mo, Jinfu Ma and Hongan Liu. 2018. A New Middle Jurassic Diplodocoid Suggests An Earlier Dispersal and Diversification of Sauropod Dinosaurs. Nature Communications.9, 2700.  DOI:  10.1038/s41467-018-05128-1 

 

 

 

Introducing Akainacephalus johnsoni

Skeletal reconstructions of Akainacephalus johnsoni. From Wiersma and Irmis, 2018

The Ankylosauria is a group of herbivorous, quadrupedal, armoured dinosaurs subdivided in two major clades, the Ankylosauridae and the Nodosauridae. The group is predominantly recorded from the Late Cretaceous (Turonian—late Maastrichtian) of Asia and the last Cretaceous (early Campanian—late Maastrichtian) of western North America (Laramidia). Ankylosauridae were present primarily in Asia and North America, and the most derived members of this clade are characterized by shortened skulls, pyramidal squamosal horns, and tail clubs.

Akainacephalus johnsoni, a new genus and species of an ankylosaurid dinosaur from the upper Campanian Kaiparowits Formation of southern Utah, represents the most complete ankylosaurid specimen from southern Laramidia to date, and reveals new details about the diversity and evolution of this clade. The genus name is derived from the Greek akaina, meaning “thorn” or “spine,” referring to the thorn-like cranial caputegulae of the holotype; and “cephalus,” the Greek meaning for head. The specific epithet honors Randy Johnson, volunteer preparator at the Natural History Museum of Utah.

Skull of Akainacephalus johnsoni. From Wiersma and Irmis, 2018

The holotype (UMNH VP 20202) is a partial skeleton comprising a complete skull, both mandibles, predentary, four dorsal, four dorsosacral, three sacral, one caudosacral, and eight caudal vertebrae, dorsal ribs, a complete tail club, both scapulae, left coracoid, right humerus, right ulna, partial left ilium, left femur, left tibia, left fibula, phalanx, two partial cervical osteoderm half rings, and 17 dorsal and lateral osteoderms of various sizes and morphologies.

The most striking feature of Akainacephalus johnsoni is the skull ornamentation comprising several symmetrical rows of small pyramidal and conical caputegulae along the dorsolateral surface of the skull. The postorbital horns are dorsoventrally tall, backswept, and project laterally in dorsal view. The quadratojugal horns display an  asymmetrical triangular morphology with a vertically positioned apex. Only a partial squamosal horn is preserved, but is largely broken.

Life reconstruction of Akainacephalus johnsoni (Image credit: Andrey Atuchin and the Denver Museum of Nature & Science)

The unique anatomical features of Akainacephalus johnsoni indicate a close taxonomic relationship with Nodocephalosaurus kirtlandensis, that clearly distinguish them from other Late Cretaceous Laramidian (although both taxa are temporally separated by nearly three million years). Because both taxa a more closely related to Asian ankylosaurids, the geographic distribution of Late Cretaceous ankylosaurids throughout the Western Interior could be the result of several geologically brief intervals of lowered sea level that allowed Asian ankylosaurid dinosaurs to immigrate to North America several times during the Late Cretaceous. The dispersal of ankylosaurids into Laramidia is coeval with the dispersal of other dinosaur clades, like tyrannosaurids and ceratopsians. The climate gradients and the fluctuations in sea level, may have helped reinforced Campanian provincialism.

 

References:

Wiersma JP, Irmis RB. (2018) A new southern Laramidian ankylosaurid, Akainacephalus johnsoni gen. et sp. nov., from the upper Campanian Kaiparowits Formation of southern Utah, USA. PeerJ 6:e5016 https://doi.org/10.7717/peerj.5016

Arbour, V. M.; Currie, P. J. (2015). “Systematics, phylogeny and palaeobiogeography of the ankylosaurid dinosaurs”. Journal of Systematic Palaeontology: 1–60. doi: 10.1080/14772019.2015.1059985