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F I G U R E 5 in Heterochrony and the evolution of the longjaw mudsucker (Gobiidae, Teleostei)

F I G U R E 5 Hypothesized phylogeny and inferred patterns of heterochrony between Eucylcogobius and Gillichthys.

F I G U R E 2 in Heterochrony and the evolution of the longjaw mudsucker (Gobiidae, Teleostei)

F I G U R E 2 Scatter plot of principal component 1 score (representative of body size) for all three species against (a) log-transformed total jaw length and (b) log-transformed free maxilla length. Linear trendline shown as lines matching the colors for each species. Sex is shown with different shapes for each species.

F I G U R E 3 in Heterochrony and the evolution of the longjaw mudsucker (Gobiidae, Teleostei)

F I G U R E 3 Scatter plot of principal component 1 score (representative of body size) for mature and juvenile (a) Gillichthys mirabilis against log-transformed total jaw length, (b) G. mirabilis against log-transformed free maxilla length, (c) Gillichthys seta against log-transformed total jaw length, (d) G. seta against log-transformed free maxilla length, (e) Eucyclogobius newberryi against log-transformed total jaw length, and (f) E. newberryi against log-transformed free maxilla length. Linear trendlines shown with corresponding equations matching the colors for each sex.

F I G U R E 4 in Heterochrony and the evolution of the longjaw mudsucker (Gobiidae, Teleostei)

F I G U R E 4 Scatterplot of principal components 1 and 2 from a principal component analysis of sexually mature Gillichthys mirabilis, Gillichthys seta, and Eucyclogobius newberryi (morphometric data adjusted using allometric- Burnaby transformation). Ellipses represent 95% confidence intervals.

F I G U R E 1 in Heterochrony and the evolution of the longjaw mudsucker (Gobiidae, Teleostei)

F I G U R E 1 Photos of a preserved Gillichthys mirabilis (a) unlabeled and (b) with labeled landmarks used in geometric morphometric analysis (in blue): (1) anterior tip of nasal bone, (2) first dorsal-fin spine insertion, (3) insertion of first element of second dorsal fin, (4) upper tip of dorsal hypural plate, (5) lower tip of ventral hypural plate, (6) first anal-fin spine insertion, and (7) pelvic-fin spine base. Additional measurements used in geometric morphometric analysis (in green): (1) head length from snout to farthest posterior point of the operculum, (2) head length from snout to dorsal operculum insertion, (3) total upper jaw length, (4) free maxilla length or the posterior portion of the maxilla that is not attached to the head, (5) maximum maxilla depth, and (6) body depth at the origin of the anal fin.

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Scan files, 3D reconstructions, data spreadsheet and supplementary files for Heterochrony and parallel evolution of echinoderm, hemichordate and cephalochordate internal bars

Deuterostomes comprise three phyla with radically different body plans. Phylogenetic bracketing of the living deuterostome clades suggests the latest common ancestor of echinoderms, hemichordates and chordates was a bilaterally symmetrical worm with pharyngeal openings, with these characters lost in echinoderms. Early fossil echinoderms with pharyngeal openings have been described, but their interpretation is highly controversial. Here, we critically evaluate the evidence for pharyngeal structures (gill bars) in the extinct stylophoran echinoderms Lagynocystis pyramidalis and Jaekelocarpus oklahomensis using virtual models based on high-resolution X-ray tomography scans of three-dimensionally preserved fossil specimens. Multivariate analyses of the size, spacing and arrangement of the internal bars in these fossils indicate they are substantially more similar to gill bars in modern enteropneust hemichordates and cephalochordates than to other internal bar-like structures in fossil blastozoan echinoderms. The close similarity between the internal bars of the stylophorans L. pyramidalis and J. oklahomensis and the gill bars of extant chordates and hemichordates is strong evidence for their homology. Differences between these internal bars and bar-like elements of the respiratory systems in blastozoans suggest these structures might have arisen through parallel evolution across deuterostomes, perhaps underpinned by a common developmental genetic mechanism.

Fig. 3 in Early Jurassic anoxia triggered the evolution of the oldest holoplanktonic gastropod Coelodiscus minutus by means of heterochrony

Fig. 3. Correlation between the shell thickness and shell diameter; by linear bivariate modelling using Ordinary Least Squares Regression in PAST3 (Hammer et al. 2001). A. The data show that the shell of Coelodiscus minutus is generally very thin and shows a linear increase with shell diameter; this linear increase is generally typical of shelled molluscs and is also present in modern holoplanktonic gastropods. B. The log-transformed data of the original measurements confirm the linear increase with shell diameter. Abbreviations: N, number of bootstrap replicates; n, number of measured specimens; R2, coefficient of correlation; p, permutation test on correlation (R2), using 9999 replicates.

Fig. 2 in Early Jurassic anoxia triggered the evolution of the oldest holoplanktonic gastropod Coelodiscus minutus by means of heterochrony

Fig. 2. Occurrence and morphology of the holoplanktonic gastropod Coelodiscus minutus (Schübler in Zieten, 1833), Posidonia Shale Formation, Lower Toarcian; Altdorf near Nuremberg, Northern Bavaria, Southern Germany. A. BSPG 2008 XXIX 36a, superabundance in the limestone concretions. B. BSPG 2008 XXIX 56f, lowspired shell, wider than high. C. BSPG 2008 XXIX 42a, elevated but somewhat depressed spire. D. BSPG 2008 XXIX 26a, abrupt transition from protoconch to teleoconch. E. BSPG 2008 XXIX 56c, fine spiral lirae separated by wide interspaces. F. BSPG 2008 XXIX 56a, opisthocyrt growth lines with the backmost point situated in adapical direction. G. BSPG 2008 XXIX 24a, growth abnormality represented by loss of ornamentation. H. BSPG 2008 XXIX 42c, growth abnormality represented by a swell of the shell. I. BSPG 2008 XXIX 62c, small specimen with well-preserved sculpture ensuring an attribution to C. minutus.

Fig. 4 in Early Jurassic anoxia triggered the evolution of the oldest holoplanktonic gastropod Coelodiscus minutus by means of heterochrony

Fig. 4. Fossil content beside the Coelodiscus minutus shells, Posidonia Shale Formation, Lower Toarcian; Altdorf near Nuremberg, Northern Bavaria, Southern Germany. A. BSPG 2008 XXIX 69h, articulated bivalve prodissoconchs of the order Pterioida. B. BSPG 2008 XXIX 1d, valve of the epifaunal bivalve Meleagrinella substriata (Münster in Goldfuss, 1831). C. BSPG 2008 XXIX 2b, valve of the epifaunal bivalve Oxytoma sp.

Fig. 1 in Early Jurassic anoxia triggered the evolution of the oldest holoplanktonic gastropod Coelodiscus minutus by means of heterochrony

Fig. 1. The lithology of the limestone concretion, Posidonia Shale Formation, Lower Toarcian; Altdorf near Nuremberg, Northern Bavaria, Southern Germany. A. BSPG 2008 XXIX 11a, ammonite floatstone with grain-supported matrix consisting of the holoplanktonic gastropod Coelodiscus minutus (Schübler in Zieten, 1833) and fecal pellets, cemented by sparry calcite. Each of the small bright dots represents a juvenile specimen of C. minutus. B. BSPG 2008 XXIX 5a, surface of the ammonite floatstone with superabundant specimens of C. minutus.

FIGURE 3 in Heterochrony in helicoid spiral cones: a computer model for demonstrating heterochronic evolution

FIGURE 3. Modes of heterochronic change. The central simulation has parameters W0=2.5, ΔW=-0.12, D=0, S=0.8, T'0=0.4, ΔT'=0.06, and has six whorls. The other four simulations show the result of one increment of each mode of heterochronic change. The two forms on the left are paedomorphic; the forms on the right are peramorphic. Note that in this case neoteny results in larger size as the ontogenetic decline in whorl expansion is reduced, and acceleration results in a smaller size for the converse reason.

FIGURE 6. Heterochronic modelling experiment 3 in Heterochrony in helicoid spiral cones: a computer model for demonstrating heterochronic evolution

FIGURE 6. Heterochronic modelling experiment 3. The "ancestor" on the left has parameters W0=2, ΔW=-0.05, D=0, S=0.9, T'0=0.2, ΔT'=0.07, and has eight whorls. As in Figure 4, this is a common general type of gastropod shell shape. The central simulation is a "descendant" derived from this by two increments of neoteny (relative scale x 0.5); the simulation on the right has resulted from two further increments of neoteny (relative scale x 0.39). All three simulations have analogues in the Family Helicidae of the Pulmonata, and this result constitutes a hypothesis for the possible heterochronic evolution of forms with flattened spires (depressed and sub-planispiral).

FIGURE 2 in Heterochrony in helicoid spiral cones: a computer model for demonstrating heterochronic evolution

FIGURE 2. Isometric and allometric gastropods and simulations. 1, An example of a "Raupian" gastropod (Epitonium), showing isometric growth. 2, An example of a "Raupian" simulation with similar shape. 3, An example of an allometric gastropod (Megacochlea); note that there is no straight line that is tangential to the outside of all whorls. 4, A simulation using the program described here with similar shape. (Figures 2.1 and 2.3 © The Trustees of the Natural History Museum, London, reproduced from Anon, 1975, with kind permission.)

FIGURE 1 in Heterochrony in helicoid spiral cones: a computer model for demonstrating heterochronic evolution

FIGURE 1. Raup's definition of the shell dimensions on which the equations for parameters W, D and T are derived. Based on Raup (1966).

FIGURE 5. Heterochronic modelling experiment 2 in Heterochrony in helicoid spiral cones: a computer model for demonstrating heterochronic evolution

FIGURE 5. Heterochronic modelling experiment 2. The "ancestor" on the left has parameters W0=1.1, ΔW=0.05, D=0, S=2.3, T'0=2, ΔT'=-0.03, and has 10 whorls. It has a form, including the slightly concave profile of the spire, which is similar to some members of the Family Volutidae. The next simulations are "descendants" derived from this by successive increments of acceleration (relative scales x 0.5, x 0.225, x 0.0875, respectively). All of these have parallels in the Volutidae, with the final form resembling the giant volutids in the genus Melo. The observation that the simulation predicts the large size of the final form supports the heterochronic hypothesis in the evolution of these gastropods.

FIGURE 4. Heterochronic modelling experiment 1 in Heterochrony in helicoid spiral cones: a computer model for demonstrating heterochronic evolution

FIGURE 4. Heterochronic modelling experiment 1. The "ancestor" on the left has parameters W0=2.5, ΔW=-0.1, D=0, S=1, T'0=0, ΔT'=0.15, and has seven whorls. It has a general shape that is common in gastropods, and especially amongst the subclass Pulmonata. The central simulation is derived from this by one increment of acceleration (relative scale x 1.5) and the simulation on the right by two increments of acceleration (relative scale x 2). The incipient reduction in whorl diameter and incipient loss of whorl-to-whorl contact is typical of some Pulmonata, such as Family Chondrinidae. Note that if Raup's T were used, incipient reduction in whorl diameter (W<1) would lead to reversal of the translation direction, which is nonsensical; using T', this is not the case.

Figure 15 in The evolutionary significance of heterochrony in the abbreviated zoeal development of pilumnine crabs (Crustacea: Brachyura: Xanthoidea)

Figure 15. Pilumnus hirtellus (Linnaeus, 1761), telson: A, zoea I; B, zoea II; C, zoea III; D, zoea IV.

Figure 14 in The evolutionary significance of heterochrony in the abbreviated zoeal development of pilumnine crabs (Crustacea: Brachyura: Xanthoidea)

Figure 14. Pilumnus hirtellus (Linnaeus, 1761), lateral view of abdomen: A, zoea I; B, zoea II; C, zoea III; D, zoea IV.

Figure 18 in The evolutionary significance of heterochrony in the abbreviated zoeal development of pilumnine crabs (Crustacea: Brachyura: Xanthoidea)

Figure 18. The third endopod segment of the second maxilliped showing: A, seta 3.5 present; B, seta 3.5 absent.

Figure 9 in The evolutionary significance of heterochrony in the abbreviated zoeal development of pilumnine crabs (Crustacea: Brachyura: Xanthoidea)

Figure 9. Pilumnus hirtellus (Linnaeus, 1761), second maxilliped: A, zoea I; B, zoea II; C, zoea III; D, zoea IV.