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Fig. 9 in Ecophenotypic plasticity versus evolutionary trends-morphological variability in Upper Jurassic bivalve shells from Portugal

Fig. 9. Scatter plot of resilifer number over ligament length in Isognomon. The two groups that correspond to lithostratigraphy are clearly visible. Numbers in squared brackets refer to Fig. 2.

Fig. 8 in Ecophenotypic plasticity versus evolutionary trends-morphological variability in Upper Jurassic bivalve shells from Portugal

Fig. 8. Box plots of size for the three target taxa. A. Size of Arcomytilus based on log transformed geometric means of length and height. B. Size of Isognomon based on log transformed ligament length. C. Size of Eomiodon based on log transformed shell length. Arrangement of boxes corresponding more or less to their stratigraphic succession, from left to right. Numbers in squared brackets refer to Fig. 2.

Fig. 12 in Ecophenotypic plasticity versus evolutionary trends-morphological variability in Upper Jurassic bivalve shells from Portugal

Fig. 12. PCA plot of shell shape in Arcomytilus, grouped according to rib number in steps of 25 ribs and displayed as convex hulls.

Fig. 7 in Ecophenotypic plasticity versus evolutionary trends-morphological variability in Upper Jurassic bivalve shells from Portugal

Fig. 7. Scatter plots of log transformed values of height over length for the three target taxa. A. Arcomytilus. B. Isognomon. C. Eomiodon. Numbers in squared brackets refer to Fig. 2.

Fig. 6 in Ecophenotypic plasticity versus evolutionary trends-morphological variability in Upper Jurassic bivalve shells from Portugal

Fig. 6. Measured distances in the three target taxa. A. Arcomytilus. B. Isognomon. C. Eomiodon. Abbreviations: H, height; L, length; LL, ligament length. Arrow indicates turning point of growth.

Fig. 5 in Ecophenotypic plasticity versus evolutionary trends-morphological variability in Upper Jurassic bivalve shells from Portugal

Fig. 5. Specimens of neomiodontid bivalve Eomiodon securiformis (Sharpe, 1850) from the Upper Jurassic of Portugal. A–C. Sobral member, Late Kimmeridgian, E Arranhó. A. Hinge plates of left and right valve. GML 25915. B. Interior of right valve, showing hinge arrangement and parts of the muscle scars. GML 25916. C. Left valve view of articulated specimen. GML 25917. D. Articulated, strongly elongated, gerontic specimen. Sobral member, Late Kimmeridgian, Santa Cruz. GML 25918. E. Small articulated specimen with clearly visible commarginal lamellae. Alcobaça formation, Early Kimmeridgian, Vestiaria. GML 25919. F. Articulated gerontic specimen with ventrally elongated shell. Alcobaça formation, Early Kimmeridgian, Salgados. GML 25920. G. Short, rounded, articulated specimen. Sobral member, Late Kimmeridgian, E Arranhó. GML 25921. H. Large, high, and short specimen. Sobral member, Late Kimmeridgian, Porto das Barcas. GML 25922.

Fig. 3 in Ecophenotypic plasticity versus evolutionary trends-morphological variability in Upper Jurassic bivalve shells from Portugal

Fig. 3. Specimens of mytilid bivalve Arcomytilus from the Middle and Upper Jurassic of Portugal and France. A–F. Arcomytilus morrisii (Sharpe, 1850). A. Large articulated specimen with pointed umbones and slightly imprinted anterior part. Arranhó II member, earliest Tithonian, Serra de Alrota. GML 25900. B. Small adult specimen, left valve with fine ribbing pattern and relatively straight anterior margin. Alcobaça formation, Late Kimmeridgian, Consolação. GML 25901. C. Young adult specimen, left valve with coarse ribbing pattern and large, elevated disc. Arranhó II member, Early Tithonian, Santa Cruz. GML 25902. D. Small adult, articulated specimen. Alcobaça formation, Early Kimmeridgian, Salir do Porto. GML 25903. E. Large articulated specimen with extremely triangular outline and wide−spaced, strong ribs. Arranhó II member, Early Tithonian, Lameiro das Antas. GML 25904. F. Adult specimen, left valve with bi− and trifurcation and simultaneous insertion of ribs. Arranhó II member, Early Tithonian, Santa Cruz. GML 25905. G. Arcomytilus asper. Right valve. Late Bathonian, Luc−sur−Mer, Calvados, France. MNHN J 08224. H. Arcomytilus bathonicus. Right valve. Late Bathonian, Luc−sur−Mer, Calvados, France. MNHN, coll. Deshayes 1876−8. I. Arcomytilus pectinatus. Right valve. "Corallien", La Rochelle, Charente−Maritime, France. MNHN, coll. d'Orbigny 4247.

Fig. 11 in Ecophenotypic plasticity versus evolutionary trends-morphological variability in Upper Jurassic bivalve shells from Portugal

Fig. 11. Lithostratigraphy plot of Arcomytilus. A. Different species and lithostratigraphically grouped Arcomytilus morrisii are displayed as convex hulls. Calculated artificial shell outlines for full number coordinate pairs are plotted to illustrate the morphospace. M; mean artificial shell outline. B. 95% confidence ellipses of group means and corresponding calculated shell outlines for group means are plotted. Numbers in squared brackets refer to Fig. 2.

Fig. 2 in Ecophenotypic plasticity versus evolutionary trends-morphological variability in Upper Jurassic bivalve shells from Portugal

Fig. 2. Lithostratigraphy of the Upper Jurassic rock suite in the Lusitanian Basin. Modified from Schneider et al. (2009). All units discussed herein are numbered in squared brackets. Formations and members that are not yet formally established are written in lower case letters. Abbreviations: A., Arisphinctes; As., Aspidoceras; Au., Aulacostephanus; C., Crussoliceras; D., Dichotomoceras; Fm., formation; M., Micracanthoceras; Mb., member; Q., Quenstedtoceras; S., Simoceras; Se., Semiformiceras.

Fig. 1 in Ecophenotypic plasticity versus evolutionary trends-morphological variability in Upper Jurassic bivalve shells from Portugal

Fig. 1. Geographic and geological overview of the Lusitanian Basin. The numbering of localities refers to Table 1, second column.

Fig. 14 in Ecophenotypic plasticity versus evolutionary trends-morphological variability in Upper Jurassic bivalve shells from Portugal

Fig. 14. Lithostratigraphy plot of Eomiodon securiformis. A. Lithostratigraphically arranged groups are displayed as convex hulls. Calculated artificial shell outlines for full number coordinate pairs are plotted to illustrate the morphospace. M, mean artificial shell outline. B. 95% confidence ellipses of group means and corresponding calculated shell outlines for group means are plotted. Numbers in squared brackets refer to Fig. 2.

Fig. 16 in Ecophenotypic plasticity versus evolutionary trends-morphological variability in Upper Jurassic bivalve shells from Portugal

Fig. 16. Left valve of neomiodontid bivalve Eomiodon sp. from Early Tithonian, Arranhó II member, Santa Cruz (GML 25929) in internal (A) and external (B) views.

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Fig. 10 in Ecophenotypic plasticity versus evolutionary trends-morphological variability in Upper Jurassic bivalve shells from Portugal

Fig. 10. Box plot of rib numbers in Arcomytilus. Numbers in squared brackets refer to Fig. 2.

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Stepwise shifts underlie evolutionary trends in morphological complexity of the mammalian vertebral column

<p>A fundamental concept in evolutionary biology is that life tends to become more complex through geologic time, but empirical examples of this phenomenon are controversial. One debate is whether increasing complexity is the result of random variations, or if there are evolutionary processes which actively drive its acquisition, and if these processes act uniformly across clades. The mammalian vertebral column provides an opportunity to test these hypotheses because it is composed of serially-repeating vertebrae for which complexity and organization can be readily measured. Here we test seven competing hypotheses for the evolution of vertebral complexity by incorporating fossil data from the mammal stem lineage into evolutionary models. Based on these data, we reject Brownian motion (a random walk) and uniform increasing trends in favor of stepwise shifts for explaining increasing complexity. We hypothesize that clade-specific adaptations associated with increased aerobic capacity in non-mammalian cynodonts may have provided impetus for increasing vertebral complexity in mammals.</p>

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Stepwise shifts underlie evolutionary trends in morphological complexity of the mammalian vertebral column

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Data from: Phylogeny, macroevolutionary trends and historical biogeography of sloths: insights from a Bayesian morphological clock analysis

Sloths, like other xenarthrans, are an extremely interesting group of mammals that, after a long history of evolution and diversification in South America, became established on islands in the Caribbean and later reached North America during the Great American Biotic Interchange. In all three regions they were part of the impressive Pleistocene megafauna. Most taxa became extinct and only two small, distantly related tree-dwelling genera survived. Here we incorporate several recently described genera of sloths into an assembled morphological data supermatrix and apply Bayesian inference, using phylogenetic and morphological clock methods, to 64 sloth genera. Thus, we investigate the evolution of the group in terms of the timing of divergence of different lineages and their diversity, morphological disparity and biogeographical history. The phylogeny obtained supports the existence of the commonly recognized clades for the group. Our results provide divergence time estimates for the major clades within Folivora that could not be dated with molecular methods. Lineage diversity shows an early increase, reaching a peak in the Early Miocene followed by a major drop at the end of the Santacrucian (Early Miocene). A second peak in the Late Miocene was also followed by a major drop at the end of the Huayquerian (Late Miocene). Both events show differential impact at the family level. After that, a slight Plio-Pleistocene decline was observed before the marked drop with the extinction at the end of the Pleistocene. Phenotypic evolutionary rates were high during the early history of the clade, mainly associated with Mylodontidae, but rapidly decreased to lower values around 25 Ma, whereas Megalonychidae have lower values at the beginning followed by a steady increase, peaking during the Late Miocene and the Pliocene. Morphological disparity showed a similar trend, with an early increase, followed by a slowly increasing phase through the Late Oligocene and Early Miocene, and ending with another increase beginning at the middle of the Miocene. Biogeographic analysis showed southern South America as the most probable area of origin of the clade and the main region in which the early diversification events took place. Both Megatheriinae and Nothrotheriinae basal nodes were strongly correlated with Andean uplift events, whereas the early history of Mylodontidae is closely associated with southern South America and also shows an early occupation of the northern regions. Within Megalonychidae, our results show Choloepus as a descendant of an island dispersing ancestor and a probable re-ingression to South America by a clade that originated in Central or North America.

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FIGURE 25. Exechonella kleemanni n in Revision of the Recent species of Exechonella Canu & Bassler in Duvergier, 1924 and Actisecos Canu & Bassler, 1927 (Bryozoa, Cheilostomata): systematics, biogeography and evolutionary trends in skeletal morphology

FIGURE 25. Exechonella kleemanni n. sp. Red Sea (A‒H: holotype DPUV 2012-0004-0001). A, general view of holotype from above. B, D, close-up of several autozooids. C, lateral view of autozooids showing shape of peristomes, conical foramina, marginal pores and frontal hollow spikes. E, autozooids on colony periphery showing shape of primary orifice, conical foramina, marginal pores and multiporous mural septula (two kenozooids shown by arrows). F, G, close-up of frontal shield. H, details of primary orifice. Scale bars: A = 1 mm; B‒H = 100 µm.

FIGURE 28 in Revision of the Recent species of Exechonella Canu & Bassler in Duvergier, 1924 and Actisecos Canu & Bassler, 1927 (Bryozoa, Cheilostomata): systematics, biogeography and evolutionary trends in skeletal morphology

FIGURE 28. Actisecos discoidea (Canu & Bassler, 1929). Philippines (A, B: lectotype USNM 545923; C, D, F, paralectotype USNM 545924; E, G, paralectotype USNM 545925; H, paralectotype USNM 545927). A, B, general view of lectotype (A) and paralectotype (C) from above. B, central part of lectotype from above (ancestrula shown by arrowhead). D, F, peripheral part of colony showing peristomes (mostly broken in F) and ooecia. E, general view of paralectotype from below. G, close-up of the peripheral part of colony from below showing details of partial ooecium, basal pore chambers (some shown by arrows) with communication pores and flat kenozooids. H, details of primary orifice and frontal shield. Scale bars: A, C, E = 500 µm; B, D, F, G = 200 µm; H = 100 µm.

FIGURE 24. Exechonella spinosa Osburn, 1940 in Revision of the Recent species of Exechonella Canu & Bassler in Duvergier, 1924 and Actisecos Canu & Bassler, 1927 (Bryozoa, Cheilostomata): systematics, biogeography and evolutionary trends in skeletal morphology

FIGURE 24. Exechonella spinosa Osburn, 1940. Bermuda (A‒E: lectotype USNM 11849, A‒D, first fragment, E, second fragment). A, D, E, general view of fragments. B, primary orifice and peristome of first fragment. C, close-up of frontal shield showing foramina and broken processes. Scale bars: A = 1 mm; B‒E = 100 µm.

FIGURE 21. Exechonella nikitai n in Revision of the Recent species of Exechonella Canu & Bassler in Duvergier, 1924 and Actisecos Canu & Bassler, 1927 (Bryozoa, Cheilostomata): systematics, biogeography and evolutionary trends in skeletal morphology

FIGURE 21. Exechonella nikitai n. sp. Indian Ocean, Maldive Islands (A‒C, E, G, H: paratype DPUV 2012-0007-0006; D: paratype DPUV 2012-0007-0007; F: DPUV 2012-0007-0008). A, B, general colony view from above (in B peristomes have a sinus). C, D, lateral view of colony showing shape of peristomes and multiporous mural septulum. Kenozooids shown by arrows (in C). E, lateral view of autozooid showing shape of foramina, peristome, marginal pores and multiporous mural septulum. Kenozooid shown by arrow. F, close-up of autozooids (view from above). G, ancestrula (to the right) and two distal zooids. H, details of primary orifice and peristome. Condyle shown by arrow. Scale bars: A, B, D = 1 mm; C, E‒H = 100 µm.