Psolidium lonchostinum & Psolidium nanoplax: Two new species of Sea Cucumbers from the Brazilian Coast.

Sea Cucumbers (Holothuroidea) are a class of Echinoderms that have become elongated and worm-like, effectively becoming secondarily bilaterally symmetrical. Like all Echinoderms they have a calcareous exoskeleton, but this is greatly reduced, typically only occurring as ossicles within the epidermis. The muscle structure of Sea Cucumbers is instead supported by a layer of modified collegen that can be stiffened or relaxed at will, allowing for a more flexible body than that of other Echinoderms. The Holothuroidea fauna from the Brazilian coast is still poorly know, but efforts over the last 18 years have improved our knowledge of the Hlothuroid biodiversity.

In a paper published in the journal Zoological Studies on 4 February 2020, Luciana Martins and Marcos Tavares of the Museu de Zoologia at the Universidade de São Paulo, describe two new species of the Holothuroid genus Psolidium from São Paulo and Rio Grande do Sul. This is the first record of the genus from the Brazilian coast.

The first new species is named Psolidium lonchostinum, where 'lonchostinum' is formed by the combination of two Greek words, lonche (spear) and ostinos (bony, Latinized to ostinum), and refers to the thorn-shaped ossicles (branched rods) found in the sole. The species is described from sixteen specimens collected with the aid of a Van Veen grab and a rectangular dredge from infaunal assemblages off the coast of São Paulo.

(A)–(F) Psolidium lonchostinum. (A)–(D) Holotype (MZUSP 744). (A) upper view; (B) detail of dorsal tube feet (black arrow); (C) detail of lateral scales (white arrow); (D) ventral view; detail of ambulacral feet (note the inner and outer rows of tube feet: black and white circles, respectively); (E) paratype (MZUSP 591) detail of ventral tube feet (black arrow); (F) outline of the calcareous ring. Abbreviations: R, radial plate; IR, interradial plate. Note in (F) interradial plate entire and radial plate notched. Scale bars: (A) 4 mm; (D) 2 mm; (E) 3 mm; (F) 500 μm. Martins & Tavares (2020).

The body of Psolidium lonchostinum is flat, oval in outline, 6–8.3 mm long and 4–5.9 mm wide. The mouth and anus covered by a variable number of small and irregular scales (0.8–1 mm wide), up to two tube feet penetrate each scale dorsally and laterally. The species lacks oral and anal valves.

The marginal dorsolateral scales are 0.1–0.3 mm, smaller than the dorsal scales.The species has a thin sole, lacking scales, tube feet arranged in a double series: inner series of large tube feet and outer peripheral series of smaller tube feet close to the ventral margin, which lacks mid-ventral (sole) radial series of tube feet, except for a cluster (up to 5) posteriorly and anteriorly. The calcareous ring is simple, lacking posterior processes; radial and interradial plates united only at the base, notched only at the radial plate.

Dorsal/lateral ossicles are smooth and perforated plates, irregular in outline, with undulating margins (100–120 μm long) and round holes (5–20 μm in diameter) and branched rods (thorn ossicles) (40–60 μm long). Dorsal tube feet with perforated rods (70–130 μm long), with undulating in margins.

(A)–(F) Psolidium lonchostinum, holotype (MZUSP 744). Scanning electron microscope photomicrographs of the ossicles. (A) scale from dorsal body wall, showing canals for tube feet (white arrow); (B) smooth plate from dorsal body; (C) branched rods (thorn ossicle) (black arrow); (D) rod from dorsal tube feet; (E)–(F) knobbed plates from sole. Scale bars: (A)–(B) 50 μm; (C) 40 μm; (D)–(F) 50 μm. Martins & Tavares (2020).

The sole of Psolidium lonchostinum is covered with single-layered and elongated plates (130–150 μm long), perforated at their entire length and knobbed at center and margins, and smooth plates slightly knobbed in the margin (70–100 μm long). Ventral tube feet with perforated rods with irregular, curved and undulating margins (80–160 μm long) and an end-plate.

(A)–(F) Psolidium lonchostinum, holotype (MZUSP 744). Scanning electron microscope photomicrographs of the ossicles. (A) four-holed smooth plate from sole, ventral view; (B) four-holed smooth plate from sole, dorsal view; (C)–(D) multiperforated smooth plate from sole, dorsal view; (E) four-holed smooth plate from sole, lateral view; (F) rod from ventral tube feet, dorsal view. Scale bars: (A)–(B) 30 μm; (C) 40 μm; (D)–(E) 50 μm; (F) 80 μm. Martins & Tavares (2020).

The second species is named Psolidium nanoplax, where 'nanoplax' is formed by the Greek words, nano (little) and plax (plate), in reference to the reduced length of the sole plates. The species is described from two specimens collected from the offshore part of the Campos Basin of southeastern Brazil, with the aid of an ELOS dredge.

(A)–(F) Psolidium nanoplax (MZUSP 589, 592). (A) Lateral view of holotype preserved in ethanol (note anal cone in white arrow); (B) upper view of paratype-MZUSP 592 preserved in ethanol (note mouth and anus in black and red arrows, respectively); (C) detail of anal cone holotype-MZUSP 592 (note anal cone and papillae, in white and red arrows, respectively); (D) detail of dorsal tube feet holotype-MZUSP 592 (red arrow); (E) detail of lateral scales paratype-MZUSP 592; (F) ventral view detail of ambulacral feet paratype-MZUSP 592, (note the inner and outer rows of tube feet: black and white arrows, respectively); (G) calcareous ring (H) detail of retractor muscle (white arrow) and (I) outline of the calcareous ring paratype-MZUSP 592. Abbreviations: R, radial plate; IR, interradial plate. Note, only radial plate notched. Scale bars: (A) 5 mm; (B) 4 mm; (C) 500 μm, (D) 500 μm, (E) 0.5 mm; (F) 2 mm; (G)–(I) 500 μm. Martins & Tavares (2020).

The body of the first of the specimens was elongate, reaching 11 mm, the smaller was ventrally and dorsally flattened and measured 8 mm. Ths mouth and anus lack valves, the anal cone is slightly raised. The dorsal and lateral body are covered with conspicuous imbricating scales (0.8–1 mm) and without granules or tubercles at the surface. One inconspicuous tube foot is present at each scale. The marginal dorsolateral scales smaller than dorsal scales (0.1–0.3 mm). Ventral sole lacking scales, tube feet arranged in a double series: inner series of large tube feet and outer peripheral series of smaller tube feet close to ventral margin, mid-ventral tube feet absent. Calcareous ring simple, lacking posterior processes, radial and interradial plates united only at the base; radial plate notched.

The dorso-lateral ossicles are knobbed and multiperforated single plates, flat, oval in outline, heavily knobbed on one side, smooth on the other surface, knobbed edges (150–170 μm long) and rounded holes 10–20 μm in diameter.

(A)–(I) Psolidium nanoplax (MZUSP 589). Scanning electron microscope photomicrographs of the ossicles. (A) knobbed plate from dorsal body (B) supporting rod from dorsal tube feet; (C) 'cup-like' plates from sole in dorsal view; (D) 'cup-like' multiperforated plates from sole in ventral view; (E) 'cup-like' four-holed plates from sole in dorsal view; (F) 'cup-like' plates from sole in lateral view (G) knobbed plates from sole and (H)–(I) knobbed plates from ventral tube feet. Scale bars: (A)–(B) 50 μm; (C) 20 μm; (D)–(I) 30 μm. Martins & Travares (2020).

The sole is covered with with knobbed and multiperforated single plates, strongly concave, oval in outline, heavily knobbed on one side, smooth on the other surface, knobbed edges (70–100 μm long), and round holes 15–20 μm in diameter and 'cup-like' multiperforated plates, concave, oval in outline (50–70 μm long) 10–15 μm in diameter. 

Dorsal tube feet with supporting rods, curved with one central perforation and one central apophysis (80–150 μm). Ventral tube feet with knobbed and multiperforated plates.

See also...

Follow Sciency Thoughts on Facebook.

Dynamosuchus collisensis: A new species of Ornithosuchid Pseudosuchian from the Late Triassic Santa Maria Formation of Rio Grande do Sul, Brazil.

The radiation of Pseudosuchian Archosaurs during the Triassic Period is characterized by the origin and extinction of several peculiar and disparate clades, such as Aetosauria, Erpetosuchidae, Gracilisuchidae, and Ornithosuchidae. The latter is one of the most enigmatic clades. Coined by Friedrich von Huene in 1908, the Ornithosuchidae have a long and controversial taxonomic history. The clade has been placed in different phylogenetic positions across the Archosauria. Nevertheless, most hypotheses have converged on a position near the base of Pseudosuchia. Three species form the clade: Ornithosuchus woodwardi, from the late Carnian–early Norian Lossiemouth Sandstone Formation of Scotland, Venaticosuchus rusconii, from the late Carnian Ischigualasto Formation of Argentina, and Riojasuchus tenuisceps, from the Norian Los Colorados Formation of Argentina. All members of this group are interpreted to have been carnivorous, putatively scavengers and facultatively bipedal during fast movement. Nevertheless, the fossil record of the group is geographically limited and so far, no remains outside Ischigualasto-Villa Union Basin pf Argentina or the Lossiemouth Sandstone Formation of Scotland have been identified, thus leaving a large gap in their potential biogeographic distribution.

In a paper published in the journal Acta Palaeontologica Polonica on 31 January 2020, Rodrigo Müller of the Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia at the Universidade Federal de Santa Maria, Maria Belén Von Baczko and Julia Desojo of the División Paleontología de Vertebrados at the Museo de La Plata, and Sterling Nesbitt of the Department of Geosciences at Virginia Tech describe the first partial skeleton of an Ornithosuchid from the Late Triassic sediments of Brazil and explore its phylogenetic affinities and implications for the evolution of the group.

(A) Location map of the Janner site and the surface distribution of the geologic units in the area. (B) Stratigraphic column of the Janner site depicting its fossiliferous content: (1) Exaeretodon; (2) Hyperodapedon; (3) Pampadromaeus; (4) Trucidocynodon; (5) Bagualosaurus; and (6) the new Ornithosuchid. Müller et al. (2020).

The specimen comes from the Santa Maria Formation at the the Janner site, which is located at the base of the Agudo Hill in the Paraná Basin of Rio Grande do Sul State, Brazil. The location is considered to be Carnian in age (237 to 227 million years old), based upon the presence of Hyperodapedon and Exaeretodon, which are also known from sites elsewhere in Brazil and Argentina with well constrained dates.

The specimen is a partial skeleton including the premaxillae, the left maxilla, both frontals, the right postfrontal, the right parietal, both squamosals, both quadratojugals, both quadrates, the parabasisphenoid, both hemimandibles, some cervical, dorsal, sacral and caudal vertebrae, several ribs, gastralia, and osteoderms, the left scapula, both forelimbs, the left ilium, the right pubis, left femur, the right tibia, and the left fibula. It is named Dynamosuchus collisensis, where 'Dynamosuchus' means 'power-Crocodile' and 'collisensis' means 'from the hill'.

Representative skeletal elements of the Ornithosuchid Archosaur Dynamosuchus collisensis (CAPPA/UFSM 0248) from Janner outcrop, Carnian, Late Triassic. (A) Selected skull bones in left lateral view. (B) Reconstruction of the skull. (C) Skull in ventral view. (D) Left quadrate and quadratojugal in posterodorsal view. (E) Parabasisphenoid in left lateral view. (F) Neural arch of an anterior cervical vertebra in anterior view. (G) Centrum of a cervical vertebra in left lateral view. (H) Right osteoderm in dorsal view. (I) Neural arch of an anterior dorsal vertebra in left lateral view. (J) Left ilium in lateral view. (K) Reconstruction of the skeleton of CAPPA/UFSM 0248 (preserved elements indicated in orange) (L) Right humerus in anterior view. (M) Right forearm in medial view. (N) Left manus in dorsal view. (O) Right (reversed) pubis in lateral view. (P) Left femur in anterior view. (Q) Left fibula in lateral view.  Scale bars 20 mm. Müller et al. (2020).

A phylogenetic analysis recovered 18 most parsimonious trees of 3356 steps each. In all the most parsimonious trees, Dynamosuchus collisensis nests within Ornithosuchidae. Ornithosuchus woodwardi lies as the basal-most member of Ornithosuchidae. The clade is supported by 19 synapomorphies, such as the alveolar margin of the premaxilla not reaching the contact with the maxilla, three premaxillary teeth, mandibular symphysis present along one-third of the lower jaw, three sacral vertebrae, a perforated acetabulum, and the presence of the anterior trochanter on the femur. Dynamosuchus collisensis was found as the sister taxon of Venaticosuchus rusconii and this is supported by the semilunar depression on the posterolateral surface of the parabasisphenoid and ascending process of the quadratojugal moderately anterodorsally to posteroventrally oriented in an angle higher than 40°. The clade including both taxa is the sister group of Riojasuchus tenuisceps. This arrangement relies in the strongly downturned main body of the premaxilla and the strongly anteroposteriorly expanded distal end of the radius. The Ornithosuchidae is found as the sister taxon of the Erpetosuchidae, whereas the clade comprising both these groups is found as the sister taxon of the Aetosauria.

Macroevolutionary patterns of Ornithosuchidae. (A) Time-calibrated reduced strict consensus tree depicting the phylogenetic position of Dynamosuchus collisensis. Numbers on nodes represent Bremer support values higher than one. Numbers associated with the Ornithosuchid branch represent the characters and states that support the clade. (B) Geographical distribution of Ornithosuchids across the time. (C) Life reconstruction of Dynamosuchus collisensis. Müller et al. (2020).

Ornithosuchids, first described at the end of the 19th century, were important for deciphering the relationships among basal Archosaurs because of their controversial anatomical features. However, no other Ornithosuchids have been found since Venaticosuchus rusconii was discovered in Argentina almost a half century ago. Furthermore, Dynamosuchus collisensis is the first unambiguous Ornithosuchid from Brazil.

The presence of Ornithosuchids in Upper Triassic beds from Brazil is not a surprise, as the group is recorded in coeval strata of Argentina (i.e. Venaticosuchus rusconii). The age of the strata that yielded Dynamosuchus collisensis is similar to that of the levels in which Ornithosuchus woodwardi from Scotland and Venaticosuchus rusconii from Argentina were found, as these strata have also yielded remains of the Rhynchosaur Hyperodapedon, which is extensively adopted as index fossil of Carnian age.The other known Ornithosuchid, Riojasuchus tenuisceps, was exhumed from the Los Colorados Formation, Argentina, which is Norian in age ( 227 to 208.5 million years old). Therefore, Dynamosuchus collisensis falls within the stratigraphic range of the oldest known Ornithosuchids.

The close relationship between Venaticosuchus rusconii and Dynamosuchus collisensis reinforces the previous proposed biostratigraphic hypotheses, indicating a similar faunal assemblage in both contemporaneous Paraná and Ischigualasto-Villa Unión basins. Moreover, the sister taxon affinity between Venaticosuchus rusconii and Dynamosuchus collisensis rejects a potential endemic radiation of ornithosuchids from the Ischigualasto-Villa Unión Basin and would better support multiple diversification events, at least at the Carnian. Indeed, the phylogenetic affinities of Proterochampsid Archosauriforms and Erpetosuchids would also suggest multiple dispersal events between the Ischigualasto-Villa Unión and the Paraná basins with the simultaneous appearance of several closely-related species in both basins (i.e. the Argentinean Proterochampsids Proterochampsa barrionuevoi and Pseudochampsa ischigualastensis, and the Brazilian Rhadinosuchus gracilis and Proterochampsa nodosa; the Brazilian Erpetosuchids Archeopelta arborensis and Pagosvenator candelariensis and the Argentinean Tarjadia ruthae). In addition, the presence of an Ornithosuchid in Brazil expands the longitudinal distribution of the group, suggesting that Ornithosuchids were more widespread than previously thought in the southern hemisphere. No records of the group have been found in lower latitudes close to the Paleo-Equator, however, age equivalent formations or localities are very scarce. Therefore, Ornithosuchids are still restricted to higher latitudes of northern and southern Pangea.

The discovery of Dynamosuchus collisensis in the Paraná Basin also provides novel paleoecological implications for this type locality (the Janner site). Strictly carnivorous Reptiles were previously absent from this site, as the early Sauropodomorph Pampadromaeus barberenai was more likely to be an omnivorous animal according to a recent ecomorphological analysis. On the other hand, Bagualosaurus agudoensis is more related to post-Carnian Sauropodomorphs, which are considered herbivorous or omnivorous. Therefore, strictly carnivorous animals are solely represented in the site through the record of Ecteniniid Cynodonts. Indeed, Ornithosuchids have been considered as top tier predators. However, recently the feeding behavior of these animals have been explored through more rigorous techniques (i.e., quantitative approaches), indicating that Ornithosuchids likely adopted scavenging feeding habits or preyed only on small Vertebrates. Such statement relies on the elevated bite force together with the low bite speed and the morphology of their constricted snouts. Therefore, the discovery of Dynamosuchus collisensis provides the first clue of a putative necrophagous vertebrate from the Janner site and expands our knowledge regarding the trophic chain of Late Triassic of Brazil. This is particularly interesting because necrophagous animals are an important part of the extant terrestrial ecosystems, interacting with the carcasses before its incorporation within the lithosphere. Therefore, identifying the animals that played such role in ancient environments is crucial for the reconstruction of reliable pictures of these. Indeed, the Janner site has yielded evidences of osteophagic behavior by Insects and the putative action of necrophagous animals that produced an accumulation with predominance of cranial elements.

Dynamosuchus collisensis is the first unambiguous member of Ornithosuchidae from Brazil, and was recovered as sister taxa of the Argentinean taxon Venaticosuchus rusconii. This sister taxon relationship would support multiple radiation events between Paraná and Ischigualasto-Villa Unión basins in agreement with previous hypothesis based on other Archosauriforms that are shared across these basins. The discovery of an Ornithosuchid in Carnian continental outcrops of Brazil provides a new shared faunal component between the basins. The Carnian Archosauromorph communities of Argentina and Brazil would therefore consist of Rhynchosaurs, Proterochampsids, Ornithosuchids, Aetosaurs, Rauisuchians, Erpetosuchids, Sauropodomorphs, and Theropods. In addition, the discovery of Dynamosuchus collisensis provides the first clue of a putative necrophagous Vertebrate from the oldest Dinosaur-bearing beds and expands our knowledge regarding the trophic structure of the Late Triassic of Brazil.

See also...

Follow Sciency Thoughts on Facebook.

Landslides and flash floods kill at least fifty four in Brazil.

A series of landslides and flash floods have killed at least fifty four people in Brazil since Thursday 23 January 2020. As well as the known deaths a further eighteen people are currently missing, and over 30 000 people have been forced to flee their homes in the states of Minas Gerias, Espirito Santo, and Rio Grande do Sul. The rains began on Thursday 23 January, when over 100 mm of rain fell in twenty four hours in parts of Minas Gerias, the most rain recorded in a single day for over a century, and are predicted to continue for at least the rest of this week. Landslides are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall.

 Rescue workers search the site of a landslide in the Vila Ideal neighborhood in Belo Horizonte, Minas Gerais State, Brazil, on Friday 24 January 2020. Cristiane Mattos/Reuters.

 Southern Brazil has a rainy season that lasts from Ocotober to March, with peak rains from mid-November to mid-January, however, this year's rains have been exceptionally strong. Brazil has suffered a string of flood-related disasters in recent years, most notably in 2011, when over 800 people died. The country has a rapidly growing population, with little effective urban planning, which has led to sprawling urban developments springing up with little thought to natural hazards, and in particular poorer neighborhoods often expanding up unstable hillsides, with the result that when floods occur (which is not unusual) communities are often quickly overwhelmed. This years exceptional rains have led to more widespread flooding, which may also persist for longer, and there is a distinct danger that without determined action the death toll may exceed that of 2011.

Flooding in Belo Horizonte on 24 January 2020. TV Brasil.

This extreme weather may be linked to a developing El Niño wearther system over the Pacific Ocean. The El Niño is the warm phase of a long-term climatic oscillation affecting the southern Pacific, which can influence the climate around the world. The onset of El Niño conditions is marked by a sharp rise in temperature and pressure over the southern Indian Ocean, which then moves eastward over the southern Pacific. This pulls rainfall with it, leading to higher rainfall over the Pacific and lower rainfall over South Asia. This reduced rainfall during the already hot and dry summer leads to soaring temperatures in southern Asia, followed by a rise in rainfall that often causes flooding in the Americas and sometimes Africa. Worryingly climatic predictions for the next century suggest that global warming could lead to more frequent and severe El Niño conditions, extreme weather conditions a common occurrence.

Movements of air masses and changes in precipitation in an El Niño weather system. Fiona Martin/NOAA.

See also...

Follow Sciency Thoughts on Facebook.

Clevosaurus hadroprodon: A new species of Sphenodontian Rhynchocephalian from the Late Triassic of southern Brazil.

The Lepidosaurs are the single largest group of Amniote Vertabrates alive today, with more then 10 000 described species. However, all bar one of these are placed within one of the two subgroups which make up the Lepidosauria, the Squamates, a group which includes the Snakes, Lizards, Amphisbaenians as well as extinct groups such as the Mesozoic Mosasaurs. A second Lepidosaur group, the Rhynchocephalians, is represented today by only a single species, the Tuatara, Sphenodon punctatus, a superficially Iguana-like animal from New Zealand. Although the Tuatara resembles an Iguana, and was initially classified as a Lizard when it was discovered, it differs from Lizards in several important ways, including a fully developed third eye beneath the scales on the top of its head, a double row of teeth on the upper jaw, acrodont dentition (in which the roots of the teeth do not penetrate the jawbone) and an incomplete lower temporal bar (the bone which forms the lower part of the lateral temporal fenestra - opening in the skull behind the eyes, in Diaspids). Rhynchocephalians first appeared in the Middle Triassic, and were the most abundant and diverse group of Lepidosaurs in the Mesozoic, with the largest group of Rhynchocephalians being the Sphenodontians, although the origins of the group are not well understood.

In a paper published in the journal Scientific Reports on 14 August 2019, Annie Hsiou of the Laboratório de Paleontologia at the Universidade de São Paulo, Randall Nydam of the Arizona College of Osteopathic Medicine and Department of Anatomy at Midwestern University, Tiago Simões of the Department of Biological Sciences at the University of Alberta, and the Museum of Comparative Zoology at Harvard University, Flávio Pretto of the Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia at the Universidade Federal de Santa Maria, Silvio Onary, also of the Laboratório de Paleontologia at the Universidade de São Paulo, Agustín Martinelli of the Sección Paleontología de Vertebrados at the Museo Argentino de Ciencias Naturales ‘Bernardino Rivadavia’, and the Laboratório de Paleontologia de Vertebrados at the Universidade Federal do Rio Grande do Sul, Alexandre Liparini of the Laboratório de Pesquisas Integrativas em Biodiversidade at the Universidade Federal de Sergipe, Paulo Romo de Vivar Martínez, Marina Soares, and Cesar Schultz, also of the Laboratório de Paleontologia de Vertebrados at the Universidade Federal do Rio Grande do Sul, and Michael Caldwell of the Department of Biological Sciences and Department of Earth and Atmospheric Sciences at the University of Alberta, describe a new species of Sphenodontian Rhynchocephalian from the early Late Triassic Santa Maria Formation of Rio Grande do Sul State in southern Brazil.

The new species is described on the basis of a single sample from the Linha Bernardino outcrop, located in the outskirts of the Candelária municipality, where about six meters of fine to medium-grained sandstones, intercalated with mudstone layers and conglomerates, are exposed on the side of a ravine. Fossils here tend to occur in association with carbonate concretions. The site is noted for the production of numerous Cynodonts, from a layer dated by the uranium-lead zircon method to be 233.23 million years old. The specimen comes from a layer slightly below the Cynodonts, and is therefore assumed to be Carnian in age (237 to 227 million years old).

Location and stratigraphy interpretation. Geological map (a) of Paraná Basin in South America (upper left) and showing the Santa Maria Supersequence in Rio Grande do Sul state (southern Brazil) (detail). The Sanga do Cabral and Santa Maria Supersequences represent the geographical extent of Triassic strata. The star marks the location of the municipality of Candelária where the specimen here described comes from. Summarized stratigraphic scheme of the Linha Bernardino outcrop (b), type locality of Clevosaurus hadroprodon. Panoramic view of the Linha Bernardino type locality (c). Hsiou et al. (2019).

Zircons are volcanic minerals that form within molten rock as it cools. Like other such minerals, zircons will incorporate some elements present in the melt, but not others, notably they will incorporate uranium, but not lead. This is important because uranium is an unstable element, and over time undergoes fission, with the uranium atoms breaking down to produce, amongst other things, lead atoms. This is very useful because nuclear fission occurs at a steady rate, unaffected by conditions such as temperature or pressure, so that by comparing the proportion of uranium to lead within a zircon crystal, the time at which that crystal solidified from a liquid melt can be determined.

The new species is described from a specimen comprising an incomplete right premaxilla, an incomplete right maxilla and right lower jaw in occlusion, and left lower jaw located below these elements, a second incomplete left lower jaw, and a fragment of dentary with three isolated teeth. It is placed in the genus Clevosaurus, which has previously been described from the Late Triassic and Early Jurassic of Canada, Britain and China, and is given the specific name hadroprodon, meaning 'big first tooth'. 

Type and referred specimens of Clevosaurus hadroprodon. Photograph (a) and outline (b) of holotype partial skull (MMACR PV-027-T). Photograph (c) and outline (d) of referred partial left dentary (MMACR PV-028-T). Abbreviations: Lt Den, left dentary; Lt Mx, left maxilla; MeG, Meckel’s groove; Pmx, right premaxilla; Pmx Fac, premaxillary facet in maxilla; Rt Den, right dentary; Rt Mx, right maxilla; SB, secondary bone; D.V.Cr., dentary ventral crest; Sym, symphyseal region of dentary. Hsiou et al. (2019).

Clevosaurus hadroprodon has a large, blunt, tusk-like tooth in both the premaxilla and the first tooth position of the dentary, which gives the species its name, as well as an angled, but nearly vertical mandibular symphysis (joint between the two mandibles) and relatively deep dentary. It lacks a gap between the tusk-like tooth and the remaining dentition, a posterodorsal process of the premaxilla, well-developed medial-posteromedial expansion of the posterior dentition, flanges on the teeth, and labially expanded teeth, all features seen in other members of the genus. Importantly Clevosaurus hadroprodon shows acrodont dentition, the earliest known example of this in a Rhynchocephalian discovered to date.

Life reconstruction of Clevosaurus hadroprodon. Jorge Blanco in Hsiou et al. (2019).

See also...

Follow Sciency Thoughts on Facebook.

Macrocollum itaquii: A new species of Sauropodomorph Dinosaur from the Late Triassic of Brazil.

Sauropod Dinosaurs are the largest known land animals ever to have walked the Earth, with some species reaching masses of around 60 tonnes, larger than any member of any other Dinosaur group, and exceeded only by the modern Baleen Whales (which are fully marine in nature). These Dinosaurs descended from the Prosauropods, a polyphyletic group (i.e. a group which does not include all the descendants of their most recent common ancestor, since Sauropods are not considered to be Prosauropods; polyphyletic groups are not considered valid by many modern taxonomists) which includes early bipedal forms, and which may have split of from other Dinosaur groups before the Ornithischia/Saurischia split, with the two groups being together known as the Sauropodomorphs.

The earliest known Sauropodomorphs are relatively small-bodied forms from early Late Triassic (about 233 million years old) in Brazil, suggesting that the group originated in this area, though these forms lack many of the key features associated with the group, such as elongate necks and slender skulls.

In a paper published in the journal Biology Letters on 21 November 2018, Rodrigo Temp Müller of the Programa de Pós Graduaçaõ em Biodiversidade Animal and the Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia at the Universidade Federal de Santa Maria, Max Cardoso Langer of the Laboratório de Paleontologia at the Universidade de São Paulo, and Sérgio Dias-da-Silva, also of the Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia at the Universidade Federal de Santa Maria, describe a new species of Sauropodomorph Dinosaur from the Late Triassic of Rio Grande do Sul State, Brazil.

The new species is named Macrocollum itaquii, where ‘Macrocollum’ means ‘long-neck’ and ‘itaquii’ honours José Jerundino Machado Itaqui, for his role in the formation of the Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia. The species is described from three specimens, two almost complete and one lacking the skull and cervical vertebrae (neck). The specimens clearly show the elongate neck and slender skull of later Sauropodomorphs, and is dated to about 225 million years ago, coming from the upper portion of the Candelária Sequence of the Paraná Basin, making this species only about eight million years younger that the oldest known Sauropodomorphs. Müller et al. also suggest that the fact that three specimens were found together may be indicative that Macrocollum itaquii had began to develop social behaviour.

Reconstructed skeleton and representative elements of Macrocollum itaquii. (a) Skull in left lateral view. (b) Skull in dorsal view. (c) Skull in ventral view. (d) Fourth cervical vertebra in left lateral view. (e) Mid-truncal vertebra in left lateral view. (f) Left ilium in lateral view. (g) Left ischium in lateral view. (h) Right pectoral girdle in lateral view. (i) Right manual digit I in medial view. (j) Right astragalus in dorsal view. (k) Right femur in cranial view. (l) Left pes in cranial view. Abbreviations: I-1, phalanx one of the digit I; I-2, phalanx two of the digit I; a, angular; ap, ascending process; co, coracoid; crt, crest; ct, cranial trochanter; d, dentary; dp, diapophysis; epi, epipophysis; f, frontral; fh, femoral head; fob, fossa for the olfactoy bulbus; inf, internarial fenestra; is, ischium shaft; j, jugal; mc, medial condyle; mcI, metacarpal I; mtI, metatarsal I; mtIII, metatarsal III; mtV, metatarsal V; mw, medial wall; mx, maxilla; n, nasal; ns, neural spine; opl, obturador plate; p, parietal; pa, parapophysis; paa, postacetabular ala; pmfo, promaxillary fenestra; pmx, premaxilla; po, postorbital; poz, postzygapophysis; prf, prefrontal; prz, prezygapophysis; q, quadrate; qj, quadratojugal; sa, surangular; sac, supracetabular crest; scp, scapula; sq, squamosal; stf, supratemporal fenestra. Scale bar is 50 mm. Müller et al. (2018).

See also...

Follow Sciency Thoughts on Facebook.

CAPPA/UFSM 0179: A Dinosaur axis from one of the oldest Dinosaur-bearing sites

The axis is the second cervical vertebra, forming the first cervical vertebra, the atlas, which enables movement of the head relative to the neck, and therefore the rest of the body. Examining this bone enables palaeontologists to asses the posture of extinct animals, making it a very useful piece of the anatomy when studying groups going through periods of rapid diversification and adaption. However, as with any other part of the anatomy, this bone is not always available for study, and is under-represented in the fossil record of many key groups. One such group is the early Dinosaurs, a group which during the Middle-to-Late Triassic diversified from a small Dinosauromorph ancestor into the strikingly different Theropods, Sauropods, and Ornithischians.

In a paper published in the journal Acta Palaeontological Polonica on 12 July 2017, Rodrigo Müller of the Programa de Pós-Graduação em Biodiversidade Animal at the Universidade Federal de Santa Maria, Flávio Pretto of the Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia at the Universidade Federal de Santa Maria, Micheli Stefanello and Eduardo Silva-Neves, also of the Programa de Pós-Graduação em Biodiversidade Animal at the Universidade Federal de Santa Maria, and Sérgio Dias da Silva, also of the Centro de Apoio à Pesquisa da Quarta Colônia at the Universidade Federal de Santa Maria, describe a nearly complete Dinosaur axis bone from the early Late Triassic Buriol Outcrop of the Candelária Sequence in Rio Grande do Sul State, Brazil; the site which has produced the oldest known undisputed Dinosaur specimens.

The specimen is not assigned to or described as a species, but instead is given the designation CAPPA/UFSM 0179 (Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia/Universidade Federal de Santa Maria specimen number 0179). The preserved portion of the axis bone is 12.5 mm long, 8.5 mm wide and 8.8 mm high. It is constricted in the middle to about 4 mm by 4 mm, giving it a spindle shape, and has an attached neural spine 21.4 mm in length.

CAPPA/UFSM 0179 from the Buriol outcrop, São João do Polêsine, Rio Grande do Sul, Brazil; Carnian, late Triassic. Photographs (A₁–F₁) and schematic drawings (A₂–F₂) of the axis in left (A) and right (B) lateral, dorsal (C), ventral (D), cranial (E), and caudal (F) views. Müller et al. (2017).

The deposits which produced CAPPA/UFSM 0179 have previously produced material referred to the Lagerpetid Dinosauromorph Ixalerpeton polesinensis, and the early Sauropodomorph Buriolestes schultzi. The axis bone is not known in either of these species, so the new specimen could potentially have come from either, or another, unknown species.

Müller et al. carried out a cladistic analysis (computerised analysis of relationships within the group based entirely upon shared common features rather than assumed relationships), of the relationship of CAPPA/UFSM 0179 to other Dinosauromorphs, which suggests the bone comes from an animal close to the origins of the Theropod group.

Strict consensus tree depicting the phylogenetic position of CAPPA/UFSM 0179 and the schematic general morphology of the axis of some Triassic Dinosauriforms. Numbers below nodes represent Bremer support values (left) higher than 1 and Bootstrap values (right) higher than 50%. Abbreviation: Dinosaurifor., Dinosauriformes. Müller et al. (2017).

See also...

Follow Sciency Thoughts on Facebook.