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333 results for “Convergent evolution”
Convergent evolution of giant size in eurypterids
<p>Eurypterids, Paleozoic marine and freshwater arthropods commonly known as sea scorpions, repeatedly evolved to remarkable sizes (over 0.5 m in length) and repeatedly colonized continental aquatic habitats. We compiled data on the majority of eurypterid species and explored several previously proposed explanations for the evolution of giant size in the group including the potential role of habitat, sea surface temperature and dissolved sea surface oxygen levels using a phylogenetic comparative approach with a new tip-dated tree. Overall, there is no compelling evidence that the evolution of giant size was driven by temperature or oxygen levels, nor that it was coupled with the invasion of continental aquatic environments, latitude, or local faunal diversity. Eurypterid body size evolution is best characterized by rapid bursts of change that occurred independently of habitat or environmental conditions. Intrinsic factors likely played a larger role than previously recognized in determining the convergent origin of gigantism in eurypterids.</p>
FIGURE 20. A in Systematics and convergent evolution of multiple reef-associated Jurassic and Cretaceous crabs (Decapoda, Brachyura)
FIGURE 20. A large and small specimen of the crab Konidromites gibbus (Reuss, 1858) from the Late Jurassic (Tithonian) of Ernstbrunn, eastern Austria. A, C, E, dorsal, left-lateral, and frontal views, resp. (NHMW 2014/0194/0669). B, D, F, G, dorsal, left-lateral, frontal, and left-orbital views (NHMW 1990/0041/5104). Scale bar width equals 2.0 mm.
FIGURE 8 in Systematics and convergent evolution of multiple reef-associated Jurassic and Cretaceous crabs (Decapoda, Brachyura)
FIGURE 8. Specimen of the crab Abyssophthalmus cf. A. spinosus (von Meyer, 1842) from the Late Jurassic (Tithonian) of Ernstbrunn, eastern Austria (all except B and C) and specimens of A. spinosus from the Late Jurassic (late Oxfordian-early Kimmeridgian) of the Plettenberg quarry, Germany (B, C). A, D-H, dorsal, ventral, right-orbital (shown upside down to better see depth), frontal, left-lateral, and right-lateral views, resp. (NHMW 2014/0194/0952). B, C, dorsal views (MAB k3611 and k3607). Scale bar width is 10.0 mm, except for E (1.0 mm).
FIGURE 3 in Systematics and convergent evolution of multiple reef-associated Jurassic and Cretaceous crabs (Decapoda, Brachyura)
FIGURE 3. Length-width ratios versus maximum width of carapaces of Eodromites grandis compared to E. cristinarobinsae sp. nov. (previously identified as E. grandis). Data: Appendix 2.
FIGURE 6 in Systematics and convergent evolution of multiple reef-associated Jurassic and Cretaceous crabs (Decapoda, Brachyura)
FIGURE 6. Specimens of the crab Nodoprosopon ornatum (von Meyer, 1857) from the Late Jurassic of Central Europe. Specimens originate from the late Kimmeridgian of the Am Saufang quarry near Geisingen, SW Germany (A, C, J); the late Kimmeridgian of Bad Überkingen-Oberböhringen, SW Germany (B); the Tithonian of Ernstbrunn, eastern Austria (D-G); and the Oxfordian of Bzów (H) and Ogrodzieniec (I, K), Poland. A, B, D, E, H, I, dorsal views of carapaces (MAB k3620, SMNS 70490/3, NHMW 2014/0194/1007, 1990/0041/3475, 1535-I-F/MP/1535/1509/08, 6281-IF/MP/6281/1599/12, resp.). Note central rostral spine in A, C, and H. C, F frontal views of carapaces (NHMW 1990/ 0041/3475, MAB k3620, resp.). G, J, K, left-lateral views (NHMW 1990/0041/3475, MAB k3620, 6281-I-F/MP/6281/ 1599/12, resp.). Scale bar width equals 2.0 mm.
FIGURE 2 in Systematics and convergent evolution of multiple reef-associated Jurassic and Cretaceous crabs (Decapoda, Brachyura)
FIGURE 2. Specimens of the crab Eodromites spp. from the Late Jurassic of Europe. A, F, G, Eodromites grandis (von Meyer, 1857) from the Upper Jurassic (upper Kimmeridgian) coral limestones of Saal an der Donau in southern Germany in dorsal, frontal, and left-lateral views, resp. (SNSB-BSPG 2016 XXI 404). B-E, Holotype of Eodromites bernchrisdomiorum sp. nov. from the Upper Jurassic (lower-middle Oxfordian) deposits of Ogrodzieniec in southern Poland in dorsal, frontal, right-lateral, and orbital views, resp. (I-F/MP/6259/1588/11). E, an oblique view of right orbital structure, primarily the lateral margin with a wide fissure. H-K, Late Jurassic (Oxfordian) Eodromites bernchrisdomiorum sp. nov. from southern Poland in dorsal view (H, I-F/MP/4874/1534/08, Niegowonice, middle-late Oxfordian; I, I-F/ MP/6255/1588/11, paratype, Niegowonice, middle-late Oxfordian; J, I-F/MP/6258/1588/11, Ogrodzieniec, early-middle Oxfordian, paratype; K, I-F/MP/1369/1508/08, Bzów, middle Oxfordian). L-O, Holotype of Eodromites polyphemi (Gemmellaro, 1869) from the Late Jurassic (Tithonian) of Sicily, Italy, in dorsal, frontal, right-lateral, and left-lateral views, resp. (MGUP-020.18). Scale bar width is 5.0 mm, except for E (1.0 mm).
FIGURE 1 in Systematics and convergent evolution of multiple reef-associated Jurassic and Cretaceous crabs (Decapoda, Brachyura)
FIGURE 1. Pits and muscle scars present on the dorsal carapace of some brachyuran crabs and referred to in the manuscript, particularly for Tanidromites Schweitzer and Feldmann, 2008a, and Eodromites Patrulius, 1959. Modified after Starzyk (2015b, figure 2.1). Unmarked black circles represent tubercles.
FIGURE 15 in Systematics and convergent evolution of multiple reef-associated Jurassic and Cretaceous crabs (Decapoda, Brachyura)
FIGURE 15. Holo- and paratype of the crab Protuberosa protuberosa (Wehner, 1988) from the Late Jurassic (late Kimmeridgian) of Saal near Kelheim, southern Germany. A, B, dorsal views of carapace of holotype (SNSB-BSPG 2016 XXI 482) (external mold and cast, resp.). C, dorsal view of partial carapace of paratype (SNSB-BSPG 2016 XXI 484). D, right-lateral view of paratype. Scale bar width equals 5.0 mm.
FIGURE 19 in Systematics and convergent evolution of multiple reef-associated Jurassic and Cretaceous crabs (Decapoda, Brachyura)
FIGURE 19. Holotype and sole specimen of the crab Tanidromites nightwishorum sp. nov. (NHMW 1990/0041/3327) from the Late Jurassic (Tithonian) of Ernstbrunn, eastern Austria. A, dorsal view of carapace. B, frontal view. C, orbital view (straight on). D, left-lateral view. E, orbital view (laterally). Scale bar width is 5.0 mm, except for C and E (1.0 mm).
FIGURE 18 in Systematics and convergent evolution of multiple reef-associated Jurassic and Cretaceous crabs (Decapoda, Brachyura)
FIGURE 18. Holotype and sole specimen of the crab Tanidromites weinschenki sp. nov. (SMNS 77338) from the Late Jurassic (early Kimmeridgian) of Aalen-Wasseralfingen (Braunenberg quarry area), southwestern Germany. A, dorsal view of carapace. B, frontal view. C, left-lateral view. Scale bar width equals 2.0 mm.
FIGURE 7 in Systematics and convergent evolution of multiple reef-associated Jurassic and Cretaceous crabs (Decapoda, Brachyura)
FIGURE 7. Holotype specimen of the crab?Abyssophthalmus dzhafarberdensis (Ilyin, 2005) comb. nov. from the Late Jurassic to Early Cretaceous (Tithonian-Berriasian) of Crimea. Scale bar width equals 5.0 mm.
Comparative genomics sheds new light on the convergent evolution of infrared vision in snakes
<p>Infrared vision is a highly specialized sensory system that evolved independently in three clades of snakes. Apparently, convergent evolution occurred in the transient receptor potential ankyrin 1 (<em>TRPA1</em>) proteins of infrared-sensing snakes. However, this gene can only explain how infrared signals are received, and not the transduction and processing of those signals. We sequenced the genome of <em>Xenopeltis unicolor</em>, a key outgroup species for pythons, and performed a genome-wide analysis of convergence between two clades of infrared-sensing snakes. Our results revealed pervasive molecular adaptation in pathways associated with neural development and other functions, with parallel selection on loci associated with trigeminal nerve structural organization. Additionally, we found evidence of convergent amino acid substitutions in a set of genes, including <em>TRPA1 </em>and<em> TRPM2</em>. Analysis also identified convergent accelerated evolution in non-coding elements near 12 genes involved in facial nerve structural organization and optic nerve development. Thus, convergent evolution occurred across multiple dimensions of infrared vision in vipers and pythons, as well as amino acid substitutions, non-coding elements, genes, and functions. These changes enabled independent groups of snakes to develop and utilize infrared vision.</p>
Fig. 1 in Convergent evolution of jaws between spinosaurid dinosaurs and pike conger eels
Fig. 1. Comparative evolution of jaws between Muraenesocidae (A) and Spinosauridae (B). Craniodental morphologies of Recent pike conger eels and Cretaceous spinosaurid theropod dinosaurs are convergently similar, likely resulting from similar feeding habits. In the sister groups of Muraenesocidae and Spinosauridae, here represented respectively by Conger (Congridae) and Dubreuillosaurus (Megalosauridae), skulls exhibit the plesiomorphic condition (i.e., rostrum not markedly elongated, absence of premaxillary and dentary "rosettes", dentition homodont). The derived condition observed in both pike congers and spinosaurs, which seems to be associated with an enhanced sensitivity, can be interpreted as an adaptation to forage efficiently in aquatic environments and to grab evasive prey items such as fishes. Muraenesocidae are represented here by Muraenesox bagio (skull and head), and Spinosauridae by Baryonyx walkeri (skull) and Spinosaurus aegyptiacus (head reconstruction; courtesy of Stephen O'Connor). Characters: 1, elongated rostrum; 2, terminal "rosette" in both upper and lower jaws; 3, deep notch posterior to the upper jaw "rosette"; 4, strong heterodonty (in size); 5, "rosettes" bearing enlarged teeth. Illustrations not to scale.
Fig. 3 in Convergent evolution of two Silurian graptolites
Fig. 3. Silurian graptolite Testograptus testis (Barrande, 1850). All collections from section RC01−2, 2.5 m, Rookery Creek, Cornwallis Island. A. Largest specimen, stereopair profile and ventro−lateral view, GSC34914; A1, profile view; A2, ventro−lateral view showing long, laterally projecting thecal spines. B. Stereopair of specimen with very strong dorsal flexure and prominent keel−like protuberance at point of flexure, GSC34915. C. Lateral and ventro−distal view of specimen, GSC34916; C1, with strongly dorsally flexed nema; C2, nema strongly ventrally flexed. D. Various views of specimen GSC34917; D1, dorso−lateral view stereopair; D2, ventro−lateral view stereopair showing prominent keel−like protuberance at point of flexure; D3, ventral view; D4, dorso−lateral view, V−shaped protuberance at point of flexure. E. Steropair of specimen with strong ventral flexure and prominent protuberance distal of sicular tip, GSC34918. F. Dorso−lateral and lateral views of specimen, GSC34919; F1, dorso−lateral view showing prominent flexure; F2, profile view. Scale bars 500 µm.
Fig. 4 in Convergent evolution of two Silurian graptolites
Fig. 4. Silurian graptolites Testograptus testis (Barrande, 1850) (A, B) and Cochlograptus veles (Richter, 1871) (C–F) in direct comparison. Specimens from SB−E, 49 m, Snowblind Creek, Cornwallis Island. A. Fragment of specimen with pseudovirgula development, GSC34920; A1, stereopair showing isolated nema; A2, enlargement to show nema area, and infilling between pseudovirgula and nema. B. Stereopair of dorso−lateral view of specimen with free nema and subsequent development of rhabdosome via a pseudovirgula, GSC34921. (C–F) Cochlograptus veles (Richter, 1871); from CP98, 6.4 m, Cape Phillips, Cornwallis Island (C, F) and from CM3, 6.1 m, Cape Manning Cornwallis Island (D, E). C. Extremely well−preserved specimen, showing blunt−ended sicula and flexure; note well−developed rutellum, GSC34922. D. Ventro−lateral view of well−preserved specimen showing four complete thecae, GSC34923. E. Infrared image showing strongly curved sicula, GSC34924. F. Views of a specimen showing a pseudovirgula (arrows) and exceptionally long rutellum, GSC34925; F1, distal view enlargement; F2, SEM image; F3, infrared image.
Fig. 2 in Convergent evolution of two Silurian graptolites
Fig. 2. Silurian graptolites Cochlograptus veles (Richter, 1871) (A, B) and Testograptus testis (Barrande, 1850) (C–F) in direct comparison. Chemically cleared and infrared views of specimens from collection SJF−02, talus nodule 2A, Cape Sir John Franklin, Devon Island. A. Variously oriented views of specimens with two developed thecae and common canal of theca 3, GSC34908; A1, profile view; A2, enlargement showing normal porus; A3, dorso−lateral view; A4, ventro−lateral view. B. Ventral and lateral views of specimen, GSC34909; B1, ventral view showing tip of sicula (clear region) and well marked thickened interthecal septum (arrow); B2, profile showing well−developed nema. (C–F) Testograptus testis (Barrande, 1850). Chemically cleared and infrared images of specimens from collection RC01−2, 2.5 m, Rookery Creek, Cornwallis Island. C. Largest specimen profile showing deflexed nema distal of sicula tip, and hollow, keel−like protuberance distal of sicula tip (arrow), GSC34910. D. Profile of specimen with only gentle ventral flexure and moderately curved sicula, GSC34911. E. Near−profile view of specimen and enlargement of distal end of sicular region, GSC34913; E1, profile view of cleared specimen; E2, enlargement showing normal porus. F. Specimen with well−preserved two proximal thecae, strong ventral flexure, and hollow protuberance (arrow) distal of tip of sicula, GSC34913. Scale bars 100 µm.
Fig. 1 in Convergent evolution of two Silurian graptolites
Fig. 1. Silurian graptolite Cochlograptus veles (Richter, 1871). All collections from SJF−02, nodule 2A. A. Full profile of specimen showing theca 1 arising out of sicula very close to aperture and strong ventral flexures of nema and sicular threads, GSC34900. B. Full profile and slightly oblique view of specimen GSC 34901; B1, stereopair; B2, full profile. C. Stereopair, ventro−lateral view of specimen with complete theca 1 and protheca of theca 2, and showing free tip of sicula (arrow), GSC 34902. D. Specimen with four complete thecae and protheca of theca 5, GSC34903. E. Stereopair showing two fully developed thecae and protheca of theca 3; note well−developed rutellum, GSC34904. F. Full profile stereopair showing abrupt flexure of nema away from tip of sicula, GSC34905. G. Oblique view stereopair showing three fully developed thecae and the common canal leading to theca 4 (arrow), GSC34906. H. Stereopair distal view of fully developed thecae and protheca of theca 4, and well−developed rutellum and protuberance of sicula tip, GSC34907. Scale bars 100 µm.
Fig. 5 in Convergent evolution of two Silurian graptolites
Fig. 5. Line drawings of four monograptid species to compare thecal characteristics. A. Monograptus? cf. ayagusensis (Obut and Sobolevskaya, 1966) compressed mature specimen from Twilight Creek (TC), Bathurst Island, TC 27.5 m (Melchin 1989) showing thecae very similar to those seen in Cochlograptus veles, GSC34926. B. Cochlograptus veles (Richter, 1871), compressed mature specimen from Twilight Creek, Bathurst Island, TC 27 m (Melchin 1989), ROM46027. C. Testograptus testis incomptus (Lenz and Melchin, 1991) holotype, compressed specimen from Rookery Creek (RC), Cornwallis Island, RC 284 m (Lenz and Melchin 1991: figs. 7B, 17I), GSC95423. D. Monograptus flemingii (Salter, 1852), compressed specimen from Prairie Creek (PC), Northwest Territories, PC 210 m (Lenz 1988: pl. 1: A), GSC91494.
Fig. 6 in Convergent evolution of two Silurian graptolites
Fig. 6. Cladogram of nine species; Stimuolograptus sedgwickii used as the outgroup. Bootstrap analysis shows that all dichotomous branches have 80% or greater bootstrap support except the Monograptus flemingi–Testograptus testis subclade, which is 74%.
Fig 3 in New data on the Paleocene monotreme Monotrematum sudamericanum, and the convergent evolution of triangulate molars
Fig 3. Schematic occlusal view of two left lower molars (m1–m2) of an ornithorhynchid monotreme (Obdurodon dicksoni) (A), and a pre−tribosphenic peramuran (Peramus sp.) (B). Note the difference between the "gaps" in A and the "embrasures" in B. In the former the intermolar contact results by mesial and distal cingulids. Not to scale.
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