Soft-tissue evidence in a Jurassic ichthyosaur.

Plesiosaurus battling Temnodontosaurus (Oligostinus), front piece the Book of the Great Sea-Dragons by Thomas Hawkins.

In 1811, in Lyme Regis, one of the richest fossil locations in England and part of a geological formation known as the Blue Lias, Mary Anning and her brother Joseph unearthed the skull of an enigmatic ‘sea monster’. A year later, Mary uncovered the torso of the same specimen. The Annings sold the fossil to the Lord of the Manor of Colway, Mr. Henry Henley, for £23. The specimen was described by Sir Everard Home in 1814. Although no name was proposed for the fossil, Home concluded that it represented a transitional form between fish and crocodiles. Later, in 1819, the skeleton was purchased by Karl Dietrich Eberhard Koenig of the British Museum of London who suggested the name Ichthyosaur (“fish lizard”) in 1817.
Ichthyosaurs are extinct marine reptiles that first diversified near the end of the Early Triassic and remained one of the main predators in the Mesozoic ocean until their disappearance near the Cenomanian-Turonian boundary, 30 million years before the end-Cretaceous mass extinction. They had the largest eyes of all vertebrates, sometimes exceeding 25 cm in maximum diameter. They also have one of the earliest records of live-birth in amniotes.
 

Stenopterygius specimen from the Holzmaden quarry. Credit: Johan Lindgren

Stephen Jay Gould said that the ichthyosaur was his favourite example of convergent evolution: “Consider my candidate for the most astounding convergence of all: the ichthyosaur. This sea-going reptile with terrestrial ancestors converged so strongly on fishes that it actually evolved a dorsal fin and tail in just the right place and with just the right hydrological design. These structures are all the more remarkable because they evolved from nothing— the ancestral terrestrial reptile had no hump on its back or blade on its tail to serve as a precursor.”

During the Norian, the evolution of ichthyosaurs took a major turn, with the appearance of the clade Parvipelvia (ichthyosaurs with a small pelvic girdle). They were notably similar in appearance to extant pelagic cruisers such as odontocete whales. An exquisitely fossilized parvipelvian Stenopterygius from the Early Jurassic (Toarcian) of the Holzmaden quarry in southern Germany, indicates that their resemblance with dolphin and whales is more than skin deep.

Structure and chemistry of MH 432 blubber. From Lindgren et. al. 2018.

The specimen (MH 432; Urweltmuseum Hauff, Holzmaden, Germany) reveals endogenous cellular, sub-cellular and biomolecular constituents within relict skin and subcutaneous tissue. The external surface of the body is smooth, and was presumably comparable in life to the skin of extant cetaceans. The histological and microscopic examination of the fossil, evinced a multi-layered subsurface architecture. The approximately 100-μm-thick epidermis retains cell-like structures that are likely to represent preserved melanophores. The subcutaneous layer is over 500 μm thick, and comprises a glossy black material superimposed over a fibrous mat. The anatomical localization, chemical composition and fabric of the subcutaneous material is interpreted as fossilized blubber, a hallmark of warm-blooded marine amniotes.

 

References:

Lindgren, J., Sjövall, P., Thiel, V., Zheng, W., Ito, S., Wakamatsu, K., … Schweitzer, M. H. (2018). Soft-tissue evidence for homeothermy and crypsis in a Jurassic ichthyosaur. Nature. doi:10.1038/s41586-018-0775-x

Motani, R. (2005). EVOLUTION OF FISH-SHAPED REPTILES (REPTILIA: ICHTHYOPTERYGIA) IN THEIR PHYSICAL ENVIRONMENTS AND CONSTRAINTS. Annual Review of Earth and Planetary Sciences, 33(1), 395–420. doi:10.1146/annurev.earth.33.092203.1227

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Introducing Macrocollum itaquii.

M. itaquii, the oldest long-necked dino ever found, dating back 225 million years. (Credit: Müller et al 2018)

Sauropodomorphs were the largest land animals ever recorded in the history of life. Additionally to their colossal size, the sauropodomorph bauplan is also characterised by a small head, long neck, barrel-shaped body and columnar limbs. The group was successful and diverse, achieving a worldwide geographical distribution. Nevertheless, the rise of sauropodomorphs is still poorly understood due to the scarcity of well-preserved fossils in early Norian rocks. The Wachholz site (Caturrita Formation), in southern Brazil, is an important window to early Norian land ecosystems. This unit has yielded several sauropodomorphs, including Unaysaurus tolentinoi and the recently described Macrocollum itaquii, the oldest long-necked dinosaur known, that shed light on the rise of the group.

Discovered in 2012, from rocks belonging to the upper part of the Candelaria Sequence constrained as about 225 Ma, the three individuals described as M. itaquii are relatively well preserved. The holotype specimen (CAPPA/UFSM 0001a) consists of an almost complete and articulated skeleton. The two paratype specimens (CAPPA/UFSM 0001b and CAPPA/UFSM 0001c) are both articulated skeletons with one missing a skull and its cervical series. The clustered preservation of the three skeletons also represents the oldest evidence of gregarious behaviour in sauropodomorphs, a pattern seen in other Triassic associations, such as the ‘Plateosaurus bonebed’ from Central Europe, and the Mussaurus remains from the Laguna Colorada Formation, Argentina.

 

Skull of Macrocollum itaquii (From Müller et al 2018)

The generic name combines the Greek word macro (long) and the Latin word collum (neck), referring to the animal’s elongated neck. The specific epithet honours José Jerundino Machado Itaqui, one of the main actors behind the creation of CAPPA/UFSM (Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia/Universidade Federal de Santa Maria).

M. itaquii was only 3.5 meters long and weighed about 101.6 kilograms, and differs from all other known sauropodomorphs in possessing the following characters: antorbital fossa perforated by a promaxillary fenestra; medial margin of the supratemporal fossa with a simple smooth curve at the frontal/parietal suture; proximal articular surface of metacarpal I transversely narrow; acetabulum not fully open; ischiadic longitudinal groove not reaching the caudal half of the ischium; absence of trochanteric shelf on the femur; medial condyle of distal femoral articulation subrectangular in distal view; proximal end of metatarsal II with a straight medial margin.

An artist’s impression of M. itaquii.

In contrast to most Carnian members of the group, the teeth of M. itaquii and other Norian taxa are fully adapted to an omnivore/herbivore diet. The neck elongation may also have provided a competitive advantage for gathering food resources, allowing members of the group to reach higher vegetation. The modifications of the hindlimb of M. itaquii could be related to the progressive loss of cursorial habits.

 

References:

Müller RT, Langer MC, Dias-da-Silva S. 2018, An exceptionally preserved association of complete dinosaur skeletons reveals the oldest long-necked sauropodomorphs. Biol. Lett. 14: 20180633. http://dx.doi.org/10.1098/rsbl.2018.0633

 

 

Introducing Mirarce eatoni, the wonderful winged messenger.

Skeletal reconstruction of Mirarce eatoni showing preserved skeletal elements (white). Illustration: Scott Hartman.

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. Among them was the long bony-tailed Jeholornis, only slightly more derived than Archaeopteryx, that lived with Sapeornis, Confuciusornis, and the earliest members of Enantiornithes.

Enantiornithes are the most diverse group of Mesozoic birds. Their remains have been collected on every continent except Antarctica, although their fossil record is particularly poor in North America and limited to the Late Cretaceous. The first probable enantiornithines from North America were collected in the 19th Century, and may be referable to Avisaurus archibaldi. Originally, A. archibaldi was described as a member of a new clade of non-avian theropod dinosaurs, the Avisauridae, the first recognized clade of enantiornithines, defined as “the common ancestor of Neuquenornis volans and Avisaurus archibaldi plus all its descendants”.

Best-preserved cervical and thoracic vertebrae, including the axis of Mirarce (From Atterholt et al., 2018)

The most complete known North American enantiornithine, the so-called “Kaiparowits avisaurid”, was collected in 1992. The specimen was recognized as a new taxon, Mirarce eatoni. Named for its spectacular preservation and level of morphological detail, the holotype (UCMP 139500) of this large, turkey-sized avisaurid enantiornithine is a three-dimensional partial skeleton consisting of several cervical and thoracic vertebrae (including the axis), the pygostyle, almost all phalanges from the left pes and several from the right, a complete humerus, femur, and tarsometatarsus, a partial scapula, coracoid, furcula, and tibiotarsus, as well as fragments of the sternum, radius, ulna, carpometacarpus, and manual phalanges.

The preserved sternal fragment of Mirarce indicates the presence of a well-developed ventral keel, very similar to that observed in Neuquenornis. In modern birds, the narrow furcula and the remige papillae, transfer aerodynamic forces from the feathers to the wing skeleton. These features were also present in Mirarce, and support the hypothesis that at least some lineages of enantiornithines convergently achieved more advanced aerial capabilities by the Late Cretaceous.

Reconstruction of living Mirarce eatoni. Illustration: Brian Engh.

The Enantiornithes have a long evolutionary history, and surviving up to the K–Pg boundary. Several trends have been suggested for the group, including: a general increase in range of body sizes; a greater degree of fusion of compound elements, and the appearance of advanced flight-related features evolved in parallel to the neornithine lineage (like manual reduction, loss of teeth, increase in size of sternal keel). It has been proposed that they were primarily forest dwellers, so they disappeared after the Chicxulub impact triggered widespread destruction of forests.

 

References:

Atterholt J, Hutchison JH, O’Connor JK. (2018) The most complete enantiornithine from North America and a phylogenetic analysis of the Avisauridae. PeerJ 6:e5910 https://doi.org/10.7717/peerj.5910

Daniel J. Field et al. Early Evolution of Modern Birds Structured by Global Forest Collapse at the End-Cretaceous Mass Extinction. Current Biology, published online May 24, 2018; doi: 10.1016/j.cub.2018.04.062

Halloween special VI: Baron Nopcsa and the dinosaurs of Transylvania

The Nopcsa Sacel Castle

Transylvania is mostly known for its myths about vampires. Following the publication of Emily Gerard’s The Land Beyond the Forest (1888), Jules Verne published Le Château des Carpathes (The Castle of the Carpathians) in which Transylvania is described as one of the most superstitious countries of Europe. But of course, the most significant contribution to the development of the Transylvania place myth was Bram Stoker’s Dracula, published in 1897.

Sacel Castle, at the heart of the Hateg region, is the last residence of the Nopcsa family, known as one of the strangest in Transylvania. Among the members of the family, there were governmental counselors and chancellors of the Transylvanian Court, members of the Royal Minister and of the Royal House, and knights of imperial orders. Baron Franz Nopcsa of Felsöszilvás (1877-1933), was one of the most prominent researchers and scholars of his day, and is considered the forgotten father of dinosaur paleobiology.

Baron Nopcsa in Albanian Uniform, 1915

In 1897 Nopcsa became a student of Vienna University and by the age of 22, he presented the first description and paleobiological analysis of one of the Transylvanian dinosaurs before the Vienna Academy of Science: Telmatosaurus transsylvanicus. The holotype, BMNH B.3386, was found in the Haţeg Basin.

The Hateg region, situated at the heart of Transylvania, is the cradle of Romanian civilization, but 70 million years ago it was a tropical island in the Thetys Ocean, noted for the occurrence of aberrant, endemic, and dwarfed fauna. In 1914, Nopcsa theorized that the “limited resources” found on islands have an effect of “reducing the size of animals” over the generations. Nopcsa noted several palaeobiological features in support of his views, including what he perceived as the common presence of pathological individuals, and considered this condition a reasonable result of the ecologically impoverished and stressed environment inhabited by this fauna. The recognition of ameloblastoma in a Telmatosaurus dentary discovered from the same area represents the best documented case of pathological modification identified in Transylvanian dinosaurs.

Doda, left, and Nopcsa, circa 1931. They spent nearly 30 years together. (Hungarian Natural History Museum)

Nopcsa continued to do collecting in the Haţeg Basin, at least until the beginning of the First World War. Among the fossils that Nopcsa studied were the duck-billed Telmatosaurus transylvanicus, the bipedal and beaked Zalmoxes robustus, the armored Struthiosaurus transylvanicus, and the sauropod Magyarosaurus dacus. In addition, he made extensive travels across much of Europe to visit palaeontological museums and to meet fellow scientists. In his field trips Nopcsa was now accompanied by Elmas Doda Bajazid, whom Nopcsa met in Albania and convinced to become his secretary. The men spent nearly 30 years togheter.

On 25 April 1933, Nopcsa’s body and that of his secretary Bajazid were found at their Singerstrasse residence. Nopcsa left a letter to the police: ”The motive for my suicide is a nervous breakdown. The reason that I shot my longtime friend and secretary, Mr Bayazid Elmas Doda, in his sleep without his suspecting at all is that I did not wish to leave him behind sick, in misery and without a penny, because he would have suffered too much. I wish to be cremated.”

 

References:

David B. Weishampel & Oliver Kerscher (2012): Franz Baron Nopcsa, Historical Biology: An International Journal of Paleobiology, DOI:10.1080/08912963.2012.689745

CSIKI, Z. & BENTON, M.J. (2010): An island of dwarfs – Reconstructing the Late Cretaceous Haþeg palaeoecosystem. Palaeogeography, Palaeoclimatology, Palaeoecology 293: 265 – 270 doi:10.1016/j.palaeo.2010.05.032

Dumbravă, M. D. et al. A dinosaurian facial deformity and the first occurrence of ameloblastoma in the fossil record. Sci. Rep. 6, 29271; doi: 10.1038/srep29271 (2016).

 

 

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

 

 

 

 

 

 

 

 

 

 

 

 

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.