Fusiform Body Research Articles

Contrasting phenotypic variation among river and lake caught cisco from Great Slave Lake: Evidence for dwarf and large morphs

Coregonids are among a wide array of northern freshwater fishes that have received attention in evolutionary studies as they show phenotypic and life history variation. This intraspecific divergence is commonly manifested as dwarf and large morphs. We assessed and contrasted cisco (Coregonus artedi) in the Great Slave Lake (Northwest Territories, Canada) basin from adfluvial versus lacustrine life histories. Using conventional geometric and linear morphometric methods in conjunction with other phenotypic and life history attributes, we tested the hypothesis that the cisco in the two different environments constituted a dwarf and large species pair. River populations were sampled and compared to lacustrine from Great Slave Lake. Cluster analysis provided the strongest evidence for two phenotypic groups and these two clusters generally characterized lake and river caught cisco based on assignment success from multivariate analyses. The river form was smaller, had a more fusiform body shape, anteriorly positioned paired fins. Larger cisco showed smaller gill rakers spacing indicating that this morph may be feeding at a lower trophic level. Comparisons within river spawning groups showed that the same life history type was present in multiple rivers suggesting that human exploitation was not driving the observed life history. This study provides preliminary evidence that C. artedi exists as a species pair in Great Slave Lake. Moreover, this study adds to a growing wealth of research suggesting that the level of coregonine diversity in Great Slave Lake may rival that of the Laurentian Great Lakes prior to stock collapses.

Variation in Fast-Start Performance within a Population of Polyphenic Bluegill (Lepomis macrochirus)

Bluegill sunfish Lepomis macrochirus exhibit intraspecific variation in their morphology and swimming performance based on habitat. The pelagic form has a relatively streamlined, fusiform body shape associated with greater steady-state swimming speed and energy economy. In contrast, littoral bluegill have deeper bodies with fins located farther from their center of mass to enhance maneuverability among littoral vegetation. Deeper body shapes have been associated with increased fast-start performance to escape predators or capture prey. We hypothesized that littoral bluegill, which have a deeper body shape, would exhibit greater fast-start performance than pelagic bluegill. A total of 29 bluegill (16 littoral, 13 pelagic) were caught by hook and line, and their fast-start performance was analyzed from high-speed video recordings. Body shape appears to be a poor predictor of fast-start performance. Contrary to our expectations, pelagic bluegill had a significantly higher peak velocity, peak acceleration, and angular velocity compared to littoral bluegill. Pelagic bluegill living among larger predators and foraging on mobile prey may be exposed to selection pressures that favor increased fast-start performance. Integrated studies of internal morphology and physiology are needed to fully understand the relationship between morphology and performance in this population.

Neural adaptation to thin and fat bodies in the fusiform body area and middle occipital gyrus: An fMRI adaptation study

Visual perception can be strongly biased due to exposure to specific stimuli in the environment, often causing neural adaptation and visual aftereffects. In this study, we investigated whether adaptation to certain body shapes biases the perception of the own body shape. Furthermore, we aimed to evoke neural adaptation to certain body shapes. Participants completed a behavioral experiment (n = 14) to rate manipulated pictures of their own bodies after adaptation to demonstratively thin or fat pictures of their own bodies. The same stimuli were used in a second experiment (n = 16) using functional magnetic resonance imaging (fMRI) adaptation. In the behavioral experiment, after adapting to a thin picture of the own body participants also judged a thinner than actual body picture to be the most realistic and vice versa, resembling a typical aftereffect. The fusiform body area (FBA) and the right middle occipital gyrus (rMOG) show neural adaptation to specific body shapes while the extrastriate body area (EBA) bilaterally does not. The rMOG cluster is highly selective for bodies and perhaps body parts. The findings of the behavioral experiment support the existence of a perceptual body shape aftereffect, resulting from a specific adaptation to thin and fat pictures of one's own body. The fMRI results imply that body shape adaptation occurs in the FBA and the rMOG. The role of the EBA in body shape processing remains unclear. The results are also discussed in the light of clinical body image disturbances.

Gyrodinium moestrupii n. sp., A New Planktonic Heterotrophic Dinoflagellate from the Coastal Waters of Western Korea: Morphology and Ribosomal DNA Gene Sequence

The heterotrophic dinoflagellate Gyrodinium moestrupii n. sp. is described based on live cells and cells prepared for light, scanning electron, and transmission electron microscopy. In addition, sequences of the small subunit (SSU), internal transcribed spacers (ITS1 and ITS2), 5.8S, and the large subunit (LSU) of the rDNA were analyzed. The cells have a slender, fusiform body, taper to a sharp point at both apices, and are widest in the middle. The conical episome and hyposome are equal in size. A distinct elliptical bisected apical groove (AG) is present. Gyrodinium moestrupii has longitudinal surface striations (LSS) containing 14 and 23 lines in the episome and hyposome, respectively, whereas Gyrodinium dominans, morphologically the most similar species, has 14 and 18 lines, respectively. In addition, the episome and hyposome of G. moestrupii show distinct twists to the right and left, respectively, unlike those of Gyrodinium gutrula or G. dominans, which are not markedly twisted. The cingulum is displaced by 0.3-0.4×cell length. Length and width of cells starved for 2d were 23.9-38.2 and 12.0-18.6μm, respectively, whereas those of cells satiated with Alexandrium minutum were 30.1-61.4 and 20.7-35.6μm, respectively. The cells contain a pusule system, trichocysts, a lamellar-like structure, and a fibrous bundle, but lack chloroplasts. The SSU rDNA sequence differed by 0.2-3.9% from those of the three most closely related sequenced species for which data are currently available: G. cf. gutrula (FN669511), G. dominans (FN669510), and Gyrodinium rubrum (AB120003). The LSU rDNA was 3.2-13.9% different from G. dominans (AY571370), Gyrodinium spirale (AY571371), and G. rubrum (AY571369). The phylogenetic trees demonstrated that this novel species belongs within the Gyrodinium clade. Based on the morphological and molecular data, we propose to name it G. moestrupii n. sp.

Morphological variability of Atlantic salmon Salmo salar and brown trout Salmo trutta in different river environments

Abstract – The morphologies of sympatric juvenile Atlantic salmon Salmo salar parr and brown trout Salmo trutta parr were compared between Irish rivers with contrasting hydraulic environments – a high‐gradient and a low‐gradient tributary from the River Barrow catchment, south‐east Ireland and a high‐gradient river from the Burrishoole catchment, west of Ireland. The two catchments differ markedly in mean annual precipitation (849.0 mm year−1 and 1370.3 mm year−1 for the Barrow and Burrishoole catchments, respectively). Parr of both species demonstrated morphological variation between and within catchments. Changes in metrics such as pectoral fin length, body depth and body length between and within catchments suggest that hydraulic forces were a major determinant of morphological variation. Both species from the Burrishoole catchment had relatively larger pectoral fins, longer heads, larger eyes and shallower bodies than conspecifics from the Barrow catchment. In rivers subject to frequent rainfall‐driven high discharges, such as those in the Burrishoole catchment, a more fusiform body and head shape coupled with larger pectoral fins may reduce the energetic cost of maintaining position in the water column, as well as increase stability and manoeuvrability. The larger eyes in both parr species in the Burrishoole catchment could further be a response to the lower visibility of the more turbid and peat‐stained waters or to the reduced prey availability. The results of this study demonstrate that local adaptation to flow conditions can yield morphologically distinct populations and that multiple species can exhibit parallel phenotypic responses to changing environmental conditions.

Integration of shape and motion cues in biological motion processing in the monkey STS

To correctly perceive biological actions, the movement pattern generated in the course of the action has to be linked to the configuration of the actor. Recently, we showed that in humans, motion and configuration cues are processed separately in occipito-temporal cortex, and that both cues are integrated in the extrastriate (EBA) and fusiform (FBA) body areas (Jastorff and Orban, 2009). Using the same factorial design as in our human study, we performed fMRI experiments in awake monkeys to compare biological motion processing in the two species. Point-light displays of monkeys engaged in various actions were presented in a 2×2 factorial design. One factor manipulated the configuration of the stimuli, the other, the kinematics. As in humans, the two factors were anatomically segregated in the superior temporal sulcus (STS) rostral to the MT/V5 complex, with the effect of configuration significant along the lower bank and that of kinematics significant in the fundus and the upper bank of the STS. Moreover, voxels showing a significant interaction between the two factors were mainly confined to body-selective patches within the STS, mimicking our human findings. Importantly, this study reports for the first time differential activation for biological actions presented as point-light displays in the monkey. Moreover, our results suggest that the processing mechanisms of biological actions are remarkably similar in humans and macaque monkeys, and provide the basis for linking existing and future single-cell physiology in the monkey with human functional imaging.

Dieta y ecomorfología de la ictiofauna del arroyo Manantiales, provincia de Buenos Aires, Argentina

Diet and ecomorphology of the ichthyofauna of Manantiales stream, Buenos Aires province, Argentina. The present study addresses the correlation between diet and morphology of 19 fish species that inhabit the Manantiales stream at the headwaters of the Samborombón river, Buenos Aires province, Argentina. The species were classified into four trophic groups: carnivores, omnivores, insectivores and detritivores-alguivores. Twelve ecomorfologic attributes related to habitat use and feeding patterns were analyzed to distinguish ecomorphologic groups of species with the food consumed. Univariate and multivariate analysis techniques were used to determine groups of species using the ecomorfologic and diet attributes as descriptors. Carnivores were associated with well developed head, mouth, pectoral and caudal fins and usually presenting compressed bodies. Omnivores were a more heterogeneous group. Nektonic forms of this group were associated with a compressed body, lateral eyes and relatively small size of the pectoral fins and caudal fins; nektobentonic forms were associated with small mouth, fusiform body and long caudal peduncle; benthic forms were related to depressed body, dorsal eyes, ventral mouth and long digestive tract. The only nektonic species consuming insects on the surface is characterized by a strongly compressed body, lateral eyes, tail and big wide mouth facing up. The detritus-alguivores had a long digestive tract, mouth ventral or terminal and long caudal fin. The significant relationship between diet and ecomorphology allows to sustain that fish with similar diets converge towards common ecomorfologicic attributes.

The first skiff beetle (Coleoptera: Myxophaga: Hydroscaphidae) from Early Cretaceous Jehol Biota

The first skiff beetle fossil and earliest myxophagan,Hydroscapha jeholensisn. sp., is described and illustrated on the basis of a single specimen from the Lower Cretaceous Yixian Formation at Huangbanjigou of Beipiao City, Liaoning Province, Northeastern China. Based on the combination of diagnostic characters of this specimen (e.g., minute and fusiform body, short elytra, tapered abdomen, separated meso- and metacoxae, and 3-segmented tarsi), we suggest that it is a definitive representative of Hydroscaphidae belonging to the widespread hydroscaphid genusHydroscaphaLeConte, 1874. It also represents the only impression fossil of the beetle suborder Myxophaga. This find displays great significance for shedding light on the preservation of the minute aquatic beetles, since it is the first well-preserved impression fossil reported for the suborder, rather than amber inclusion.

A multi-gene phylogeny of Cephalopoda supports convergent morphological evolution in association with multiple habitat shifts in the marine environment.

BackgroundThe marine environment is comprised of numerous divergent organisms living under similar selective pressures, often resulting in the evolution of convergent structures such as the fusiform body shape of pelagic squids, fishes, and some marine mammals. However, little is known about the frequency of, and circumstances leading to, convergent evolution in the open ocean. Here, we present a comparative study of the molluscan class Cephalopoda, a marine group known to occupy habitats from the intertidal to the deep sea. Several lineages bear features that may coincide with a benthic or pelagic existence, making this a valuable group for testing hypotheses of correlated evolution. To test for convergence and correlation, we generate the most taxonomically comprehensive multi-gene phylogeny of cephalopods to date. We then create a character matrix of habitat type and morphological characters, which we use to infer ancestral character states and test for correlation between habitat and morphology.ResultsOur study utilizes a taxonomically well-sampled phylogeny to show convergent evolution in all six morphological characters we analyzed. Three of these characters also correlate with habitat. The presence of an autogenic photophore (those relying upon autonomous enzymatic light reactions) is correlated with a pelagic habitat, while the cornea and accessory nidamental gland correlate with a benthic lifestyle. Here, we present the first statistical tests for correlation between convergent traits and habitat in cephalopods to better understand the evolutionary history of characters that are adaptive in benthic or pelagic environments, respectively.DiscussionOur study supports the hypothesis that habitat has influenced convergent evolution in the marine environment: benthic organisms tend to exhibit similar characteristics that confer protection from invasion by other benthic taxa, while pelagic organisms possess features that facilitate crypsis and communication in an environment lacking physical refuges. Features that have originated multiple times in distantly related lineages are likely adaptive for the organisms inhabiting a particular environment: studying the frequency and evolutionary history of such convergent characters can increase understanding of the underlying forces driving ecological and evolutionary transitions in the marine environment.

Division of Labor between Lateral and Ventral Extrastriate Representations of Faces, Bodies, and Objects

The occipito-temporal cortex is strongly implicated in carrying out the high-level computations associated with vision. In human neuroimaging studies, focal regions are consistently found within this broad region that respond strongly and selectively to faces, bodies, or objects. A notable feature of these selective regions is that they are found in pairs. In the posterior-lateral occipito-temporal cortex, focal selectivity is found for faces (occipital face area), bodies (extrastriate body area), and objects (lateral occipital). These three areas are found bilaterally and at close quarters to each other. Likewise, in the ventro-medial occipito-temporal cortex, three similar category-selective regions are found, also in proximity to each other: for faces (fusiform face area), bodies (fusiform body area), and objects (posterior fusiform). Here we review some of the extensive evidence on the functional properties of these areas with two aims. First, we seek to identify principles that distinguish the posterior-lateral and ventro-medial clusters of selective regions but that apply generally within each cluster across the three stimulus kinds. Our review identifies and elaborates several principles by which these relationships hold. In brief, the posterior-lateral representations are more primitive, local, and stimulus-driven relative to the ventro-medial representations, which in contrast are more invariant to visual features, global, and linked to the subjective percept. Second, because the evidence base of studies that compare both posterior-lateral and ventro-medial representations of faces, bodies, and objects is still relatively small, we seek to provoke more cross-talk among the research strands that are traditionally separate. We identify several promising approaches for such future work.

Form and motion make independent contributions to the response to biological motion in occipitotemporal cortex

Psychophysical and computational studies have provided evidence that both form and motion cues are used in the perception of biological motion. However, neuroimaging and neurophysiological studies have suggested that the neural processing of actions in temporal cortex might rely on form cues alone. Here we examined the contribution of form and motion to the spatial pattern of response to biological motion in ventral and lateral occipitotemporal cortex, using functional magnetic resonance imaging (fMRI) and multivoxel pattern analysis (MVPA). We found that selectivity to intact versus scrambled biological motion in lateral occipitotemporal cortex was correlated with selectivity for bodies and not for motion. However, this appeared to be due to the fact that subtracting scrambled from intact biological motion removes any contribution of local motion cues. Instead, we found that form and motion made independent contributions to the spatial pattern of responses to biological motion in lateral occipitotemporal regions MT, MST, and the extrastriate body area. The motion contribution was position-dependent, and consistent with the representation of contra- and ipsilateral visual fields in MT and MST. In contrast, only form contributed to the response to biological motion in the fusiform body area, with a bias towards central versus peripheral presentation. These results indicate that the pattern of response to biological motion in ventral and lateral occipitotemporal cortex reflects the linear combination of responses to form and motion.

The role of occipitotemporal body-selective regions in person perception

The visual appearance of others’ bodies is a powerful source of information about the people around us. This information is implicit in the stimulus and must be extracted and made explicit by the coordination of activity in multiple cortical areas. Here we consider the contribution to this process of two strongly body-selective occipitotemporal regions identified in human neuroimaging experiments: the extrastriate body area (EBA) and the fusiform body area (FBA). We address the evidence and arguments behind numerous recent proposals that EBA and FBA build explicit representations of identity, emotion, body movements, or goal-directed actions from the visual appearance of bodies, and also explore the contribution of these regions to motor control. We argue that the current evidence does not support a model in which EBA and FBA directly perform any of these higher-level functions. Instead, we argue that these regions comprise populations of neurons that encode fine details of the shape and posture of the bodies of people in the current percept. In doing so, they provide a powerful but cognitively unelaborated perceptual framework that allows other cortical systems to exploit the rich, socially relevant information that is conveyed by the body.

Representation of Action in Occipito-temporal Cortex

A fundamental question for social cognitive neuroscience is how and where in the brain the identities and actions of others are represented. Here we present a replication and extension of a study by Kable and Chatterjee [Kable, J. W., & Chatterjee, A. Specificity of action representations in the lateral occipito-temporal cortex. Journal of Cognitive Neuroscience, 18, 1498-1517, 2006] examining the role of occipito-temporal cortex in these processes. We presented full-cue movies of actors performing whole-body actions and used fMRI to test for action- and identity-specific adaptation effects. We examined a series of functionally defined regions, including the extrastriate and fusiform body areas, the fusiform face area, the parahippocampal place area, the lateral occipital complex, the right posterior superior temporal sulcus, and motion-selective area hMT+. These regions were analyzed with both standard univariate measures as well as multivoxel pattern analyses. Additionally, we performed whole-brain tests for significant adaptation effects. We found significant action-specific adaptation in many areas, but no evidence for identity-specific adaptation. We argue that this finding could be explained by differences in the familiarity of the stimuli presented: The actions shown were familiar but the actors performing the actions were unfamiliar. However, in contrast to previous findings, we found that the action adaptation effect could not be conclusively tied to specific functionally defined regions. Instead, our results suggest that the adaptation to previously seen actions across identities is a widespread effect, evident across lateral and ventral occipito-temporal cortex.

Changes in “Top-Down” Connectivity Underlie Repetition Suppression in the Ventral Visual Pathway

Repetition of the same stimulus leads to a reduction in neural activity known as repetition suppression (RS). In functional magnetic resonance imaging (fMRI), RS is found for multiple object categories. One proposal is that RS reflects locally based "within-region" changes, such as neural fatigue. Thus, if a given region shows RS across changes in stimulus size or view, then it is inferred to hold size- or view-invariant representations. An alternative hypothesis characterizes RS as a consequence of "top-down" between-region modulation. Differentiating between these accounts is central to the correct interpretation of fMRI RS data. It is also unknown whether the same mechanisms underlie RS to identical stimuli and RS across changes in stimulus size or view. Using fMRI, we investigated RS within a body-sensitive network in human visual cortex comprising the extrastriate body area (EBA) and the fusiform body area (FBA). Both regions showed RS to identical images of the same body that was unaffected by changes in body size or view. Dynamic causal modeling demonstrated that changes in backward, top-down (FBA-to-EBA) effective connectivity play a critical role in RS. Furthermore, only repetition of the identical image showed additional changes in forward connectivity (EBA-to-FBA). These results suggest that RS is driven by changes in top-down modulation, whereas the contribution of "feedforward" changes in connectivity is dependent on the precise nature of the repetition. Our results challenge previous interpretations regarding the underlying nature of neural representations made using fMRI RS paradigms.

Haptic perception and body representation in lateral and medial occipito-temporal cortices

Although vision is the primary sensory modality that humans and other primates use to identify objects in the environment, we can recognize crucial object features (e.g., shape, size) using the somatic modality. Previous studies have shown that the occipito-temporal areas dedicated to the visual processing of object forms, faces and bodies also show category-selective responses when the preferred stimuli are haptically explored out of view. Visual processing of human bodies engages specific areas in lateral (extrastriate body area, EBA) and medial (fusiform body area, FBA) occipito-temporal cortex. This study aimed at exploring the relative involvement of EBA and FBA in the haptic exploration of body parts. During fMRI scanning, participants were asked to haptically explore either real-size fake body parts or objects. We found a selective activation of right and left EBA, but not of right FBA, while participants haptically explored body parts as compared to real objects. This suggests that EBA may integrate visual body representations with somatosensory information regarding body parts and form a multimodal representation of the body. Furthermore, both left and right EBA showed a comparable level of body selectivity during haptic perception and visual imagery. However, right but not left EBA was more activated during haptic exploration than visual imagery of body parts, ruling out that the response to haptic body exploration was entirely due to the use of visual imagery. Overall, the results point to the existence of different multimodal body representations in the occipito-temporal cortex which are activated during perception and imagery of human body parts.

Beyond extrastriate body area (EBA) and fusiform body area (FBA): context integration in the meaning of actions

Beyond extrastriate body area (EBA) and fusiform body area (FBA): context integration in the meaning of actions

Cryptic species of Euryakaina n. g. (Digenea: Cryptogonimidae) from sympatric lutjanids in the Indo-West Pacific

A survey of the endohelminth fauna of Indo-West Pacific Lutjanidae (Perciformes) revealed the presence of the species Siphoderina manilensis (Velasquez, 1961) Miller & Cribb, 2008 and S. marina (Hafeezullah & Siddiqi, 1970) Miller & Cribb, 2008 in seven Lutjanus spp. from sites off the Great Barrier Reef, the Maldives, New Caledonia and Ningaloo Reef, Western Australia. A combination of morphological and ribosomal DNA analyses of these cryptogonimids prompted the transfer of these taxa to a new genus, Euryakaina n. g., as E. manilensis n. comb. and E. marina n. comb., based on comparative analysis with other cryptogonimid taxa. Euryakaina n. g. is distinguished from all other cryptogonimid genera by the combination of a fusiform body, the few relatively small, widely spaced oral spines (sometimes absent), a highly lobed ovary, opposite to slightly oblique testes, vitelline follicles that extend from the anterior margin of the testes to slightly posterior to the intestinal bifurcation, and an excretory vesicle that bifurcates dorsal to the ovary and reunites briefly slightly posterior to the intestinal bifurcation. Morphometric analysis of these taxa alone suggests they should be reduced to synonymy, but DNA sequence analyses and ecological niche partitioning provide evidence that they form a cryptic species complex in sympatric lutjanids in the Indo-West Pacific. The secondary structure of the ITS2 rDNA for species of Euryakaina was also modelled and analysed for the presences of compensatory base changes (CBCs) or hemi-CBCs in order to explore the usefulness of these changes as a tool to help elucidate the taxonomy of this complex system. We also report what we interpret here as intraspecific variation in the ITS2 rDNA between individuals of E. manilensis from Lutjanus vitta recovered off the Great Barrier Reef and New Caledonia.

Differential neuronal responses to the self and others in the extrastriate body area and the fusiform body area

The extrastriate body area (EBA) and the fusiform body area (FBA) are selectively activated by viewing human bodies. However, the role of these functionally defined brain areas in self-other discrimination is still unresolved. Thirty-one females were presented with 16 pictures of their own body and another body in a bikini and with scrambled images while fMRI was performed. Moreover, standardized stimulus material was used in order to localize the EBA and FBA. Region-of-interest analysis showed an enhanced BOLD response to the self-images relative to the non-self-images in the right EBA and FBA. The right EBA and FBA are activated differently by viewing oneself and others and might thus play a role in visual self-other discrimination.

Does your EBA response to my bum look big? Differential sensitivity to body orientation in the extrastriate body area

Body orientation is an important cue to the direction of others’ attention, especially when cues from the head are insufficient or obscured. Neurophysiological research has revealed cells in macaque temporal cortex that respond selectively to different directions of seen body orientation in the absence of head or face based cues (Wachsmuth, Oram, & Perrett, 1994) and recent adaptation research suggests that humans possess a similar form of separable coding for different body directions (Lawson, Clifford, & Calder, 2009). This study employs fMRI to investigate the coding of body orientation in two previously identified body-sensitive regions of human visual cortex – the extrastriate body area (EBA) (Downing, 2001) and the fusiform body area (FBA) (Peelen & Downing, 2005). In each block, images of bodies were shown at either a front facing viewpoint (0°) or at 60°, 120° or 180° rotations away from 0°. The results showed that the EBA, but not the FBA, is sensitive to the orientation of the body, furthermore, the EBA shows a greater response to bodies oriented away from 0° (front facing). These results have implications for our understanding of the functional role of these regions in the processing of human bodies.

Convergent Evolution in Aquatic Tetrapods: Insights from an Exceptional Fossil Mosasaur

Mosasaurs (family Mosasauridae) are a diverse group of secondarily aquatic lizards that radiated into marine environments during the Late Cretaceous (98–65 million years ago). For the most part, they have been considered to be simple anguilliform swimmers – i.e., their propulsive force was generated by means of lateral undulations incorporating the greater part of the body – with unremarkable, dorsoventrally narrow tails and long, lizard-like bodies. Convergence with the specialized fusiform body shape and inferred carangiform locomotory style (in which only a portion of the posterior body participates in the thrust-producing flexure) of ichthyosaurs and metriorhynchid crocodyliform reptiles, along with cetaceans, has so far only been recognized in Plotosaurus, the most highly derived member of the Mosasauridae. Here we report on an exceptionally complete specimen (LACM 128319) of the moderately derived genus Platecarpus that preserves soft tissues and anatomical details (e.g., large portions of integument, a partial body outline, putative skin color markings, a downturned tail, branching bronchial tubes, and probable visceral traces) to an extent that has never been seen previously in any mosasaur. Our study demonstrates that a streamlined body plan and crescent-shaped caudal fin were already well established in Platecarpus, a taxon that preceded Plotosaurus by 20 million years. These new data expand our understanding of convergent evolution among marine reptiles, and provide insights into their evolution's tempo and mode.