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Thursday, February 10th, 2022
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| 1:26a | [Paleontology • 2021] Archaeovaranus lii • A New Stem-varanid Lizard (Reptilia: Varanidae) from the early Eocene of China
Abstract Monitor lizards (genus Varanus) are today distributed across Asia, Africa and Australasia and represent one of the most recognizable and successful lizard lineages. They include charismatic living species like the Komodo dragon of Indonesia and the even larger extinct Varanus prisca (Megalania) of Australia. The fossil record suggests that living varanids had their origins in a diverse assemblage of stem (varaniform) species known from the Late Cretaceous of China and Mongolia. However, determining the biogeographic origins of crown-varanids has proved problematic, with Asia, Africa and Australia each being proposed. The problem is complicated by the fragmentary nature of many attributed specimens, and the fact that the most widely accepted, and most complete, fossil of a stem-varanid, that of Saniwa ensidens, is from North America. In this paper, we describe a well-preserved skull and skeleton of a new genus of stem-varanid from the Eocene of China. Phylogenetic analysis places the new genus as the sister taxon of Varanus, suggesting that the transition from Cretaceous varaniform lizards to Varanus occurred in East Asia before the origin and dispersal of Varanus to other regions. The discovery of the new specimen thus fills an important gap in the fossil record of monitor lizards. The similar lengths of the fore- and hindlimbs in this new taxon are unusual among the total group Varanidae and suggest it may have had a different lifestyle, at least from the contemporaneous North American S. ensidens. Keywords: China, evolution, early Eocene, Varanidae
Systematic palaeontology Squamata Oppel, 1811 Anguimorpha Fürbringer, 1900 Varanidae Merrem, 1820 Archaeovaranus lii gen. et sp. nov. Etymology. The generic name Archaeo- reflects the primitive phylogenetic position of this lizard in the evolution of Varanidae, and -varanus suggests the close relationship with the genus Varanus, whereas the specific name lii honours the late Prof. Chuankui Li for his important work on Palaeogene mammals, including some from the same locality as the holotype lizard described herein. Holotype. IVPP V 22770, a nearly complete skeleton with an intact skull and associated but mostly disarticulated postcranial elements (figure 1a). Locality and horizon. Dajian locality (IVPP fossil site catalogue number 76006, ...) (...), about 35 km northwest of Danjiangkou City, Hubei Province, China; Middle Member, Yuhuangding Formation (early Eocene; 52–56 Ma; the palaeomagnetic study suggesting a precise age of 53 Ma for the fossil-bearing horizon). Diagnosis. The new genus and species is a medium-sized stem-varanid that resembles S. ensidens and Varanus and differs from helodermatids, palaeovaranids, lanthanotids and the Late Cretaceous stem-varanids in combining the following characters: posteriorly extended (retracted) external narial openings that reach frontals; a single median nasal; two lacrimal foramina, the ventral of which is fully enclosed by the lacrimal; elongated vomers; a U-shaped palatine; a short maxillary tooth row mostly confined to preorbital region, bearing well-spaced recurved teeth with basal plicidentine; intramandibular joint; splenial positioned anterior to level of dorsal prominence of the coronoid; anterior process of coronoid long; and distinct precondylar constriction on the vertebral centra. Archaeovaranus resembles S. ensidens and differs from Varanus in having cristae cranii of frontal separated in ventral midline, separate postfrontal and postorbital, a complete bony postorbital bar, teeth on palatine and pterygoid, posterolaterally placed basal tubera on basioccipital and a single coracoid emargination. It differs from S. ensidens in having a longer rostrum, two pterygoid tooth rows (versus a single row), and resembles Varanus but not Saniwa in having a dorsal lacrimal foramen enclosed by the prefrontal and lacrimal (rather than being restricted to the lacrimal). Archaeovaranus differs from both S. ensidens and known species of Varanus in having the forelimb and hindlimb, and the humerus and femur, of near equal length. Liping Dong, Yuan-Qing Wang, Qi Zhao, Davit Vasilyan, Yuan Wang and Susan E. Evans. 2020. A New Stem-varanid Lizard (Reptilia, Squamata) from the early Eocene of China. Philosophical Transactions of the Royal Society B: Biological Sciences. 377(1847); ‘The impact of Chinese palaeontology on evolutionary research’. compiled and edited by Xiaoya Ma, Guangxu Wang and Min Wang. DOI: 10.1098/rstb.2021.0041 | ||||||
| 7:28a | [Botany • 2022] Syzygium nusatenggaraense (Myrtaceae) • A New Rainforest Tree Species with A Calyptrate Calyx from the Lesser Sunda Islands, Indonesia
A new rainforest tree species of the myrtle family (Myrtaceae), Syzygium nusatenggaraense Sunarti & Y.W.Low is described here based on two collections from the Lesser Sunda Islands. This species is superficially similar to Syzygium arcanum P.S.Ashton, a Bornean endemic tree species, but differs in a suite of morphological characters and geographic distribution. The new species is illustrated, and description is here given. Keywords: endemic; Mount Batulanteh; taxonomy; Wallacea; West Nusa Tenggara Province
Syzygium nusatenggaraense Sunarti & Y.W.Low, sp. nov. Diagnosis: This species is morphologically similar to Syzygium arcanum P.S.Ashton but differs in having young twigs smooth and slightly compressed (vs angular and sharply 4-ribbed in S. arcanum), the leaf base obtuse (vs narrowly cuneate in S. arcanum), up to 30 pairs of secondary veins with spaces in between veins c. 1 mm wide (vs up to 10 pairs and 6‒7 mm wide in S. arcanum), lower leaf surface sparsely black dotted (vs densely black dotted in S. arcanum), and flower buds obovoid with an abrupt pointed rostrum to 3 mm long (vs ovoid and without a conspicuous rostrum in S. arcanum). Etymology: The species epithet denotes the fact that the species is so far known only from Lesser Sunda Islands, where it was collected from Flores and Sumbawa. Habitat and ecology: In Flores, Syzygium nusatenggaraense was recorded from the highlands of Potjo Gurung, Ruteng at 1700 m asl (Verheijen 1963; Mees 2006); in Sumbawa, it was recorded from moist evergreen forest dominated by Dipterocarpus retusus (Dipterocarpaceae) at 500–700 m asl. Siti Sunarti, Rugayah, Yee Wen Low and Eve Lucas. 2022. Syzygium nusatenggaraense (Myrtaceae), A New Rainforest Tree Species with A Calyptrate Calyx from the Lesser Sunda Islands, Indonesia. Telopea. 25: 1–6. DOI: 10.7751/telopea15658 Satu spesies pohon hutan hujan baru dari suku jambu-jambuan atau Myrtaceae, Syzygium nusatenggaraense Sunarti & Y.W.Low diterbitkan disini berdasarkan kepada dua koleksi dari Kepulauan Nusa Tenggara. Spesies ini mirip dengan satu spesies pohon endemik Borneo Syzygium arcanum P.S.Ashton, tetapi berbeda dalam rangkaian karakter morfologi dan distribusi geografisnya. Spesies baru tersebut diilustrasikan dan deskripsi diberikan di sini. | ||||||
| 10:00a | [Paleontology • 2022] Utaurora comosa • New Opabiniid Diversifies the Weirdest Wonders of the Euarthropod Stem Group (Panarthropoda: Opabiniidae)
Abstract Once considered ‘weird wonders’ of the Cambrian, the emblematic Burgess Shale animals Anomalocaris and Opabinia are now recognized as lower stem-group euarthropods and have provided crucial data for constraining the polarity of key morphological characters in the group. Anomalocaris and its relatives (radiodonts) had worldwide distribution and survived until at least the Devonian. However, despite intense study, Opabinia remains the only formally described opabiniid to date. Here we reinterpret a fossil from the Wheeler Formation of Utah as a new opabiniid, Utaurora comosa nov. gen. et sp. By visualizing the sample of phylogenetic topologies in treespace, our results fortify support for the position of U. comosa beyond the nodal support traditionally applied. Our phylogenetic evidence expands opabiniids to multiple Cambrian stages. Our results underscore the power of treespace visualization for resolving imperfectly preserved fossils and expanding the known diversity and spatio-temporal ranges within the euarthropod lower stem group. Keywords: Opabiniidae, tree, space, Euarthropoda, Cambrian, phylogenetics, Wheeler Formation
Systematic palaeontology Superphylum PANARTHROPODA Nielsen, 1995 Family OPABINIIDAE Walcott, 1912 Diagnosis. Panarthropod with a short head region bearing a single unjointed appendage (proboscis); slender trunk with dorsally transverse furrows delimiting segments; one pair of lateral flaps per body segment; setal blades cover at least part of anterior margin of lateral flaps; caudal fan composed of multiple pairs of caudal blades; pair of short caudal rami with serrated adaxial margins. Type genus. Opabinia Walcott, 1912 Constituent taxa. Utaurora comosa nov., Opabinia regalis Walcott Utaurora nov. Etymology. Concatenation of ‘Utah', where the specimen was collected, and ‘Aurora', Roman goddess of the dawn who turned her lover into a cicada, reflecting the affinities of this taxon as an early stem group euarthropod. Type material, locality, and horizon. KUMIP 314087, part only, a complete specimen preserved compressed dorso-laterally. Collected by P. Reese from strata of the upper Wheeler Formation (Miaolingian: Drumian), at the Carpoid Quarry (GPS: 39.290417, −113.278519), southwest Antelope Mountain, House Range, Utah, USA. Diagnosis. Opabiniid with slender trunk composed of at least 13, likely 15, segments (15 in Opabinia); setal structures form blocks that cover the whole width of the trunk and proximal part of the anterior margin of the lateral flaps (setal blades only on flaps in Opabinia); tail fan composed of at least seven pairs of elongate and acuminate caudal blades (three pairs in Opabinia). Utaurora comosa gen. et sp. nov. Etymology. ‘Comosa’ (Latin = ‘hairy', ‘leafy') reflects the ‘hairy’ appearance of the dorsal surface, and caudal fan composed of many ‘leaves’.  Stephen Pates, Joanna M. Wolfe, Rudy Lerosey-Aubril, Allison C. Daley and Javier Ortega-Hernández. 2022. New Opabiniid Diversifies the Weirdest Wonders of the Euarthropod Stem Group. Proceedings of the Royal Society B: Biological Sciences. DOI: 10.1098/rspb.2021.2093 | ||||||
| 2:22p | [Mammalogy • 2022] Genomic Basis for Skin Phenotype and Cold Adaptation in the Extinct Steller’s Sea Cow Hydrodamalis gigas
Abstract Steller’s sea cow, an extinct sirenian and one of the largest Quaternary mammals, was described by Georg Steller in 1741 and eradicated by humans within 27 years. Here, we complement Steller’s descriptions with paleogenomic data from 12 individuals. We identified convergent evolution between Steller’s sea cow and cetaceans but not extant sirenians, suggesting a role of several genes in adaptation to cold aquatic (or marine) environments. Among these are inactivations of lipoxygenase genes, which in humans and mouse models cause ichthyosis, a skin disease characterized by a thick, hyperkeratotic epidermis that recapitulates Steller’s sea cows’ reportedly bark-like skin. We also found that Steller’s sea cows’ abundance was continuously declining for tens of thousands of years before their description, implying that environmental changes also contributed to their extinction.
Hydrodamalis gigas Zimmermann, 1780 Diana Le Duc, Akhil Velluva, Molly Cassatt-Johnstone, ... et Torsten Schöneberg. 2022. Genomic Basis for Skin Phenotype and Cold Adaptation in the Extinct Steller’s Sea Cow. SCIENCE ADVANCES. 8, 5. DOI: 10.1126/sciadv.abl6496  |
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