Drifting with trilobites: The invasion of early post-embryonic trilobite stages to the pelagic realm

Laibl, Lukáš; Saleh, Farid; Pérez-Peris, Francesc

doi:10.1016/j.palaeo.2023.111403

Cited by 17 publications

(13 citation statements)

References 91 publications

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“…While dispersal influenced the movement and distribution of trilobites throughout the Ordovician (Chatterton and Speyer 1989;Perrier et al 2015;Lam et al 2018), the communities of the central Anti-Atlas region appear controlled by these dispersal forces to a lesser degree than many other neighboring regions (Saleh et al 2022a), as reflected in the slight percentage increase in taxa with planktonic larvae we observe between the Fezouata Shale sections (+10%). Regardless of the magnitude of this increase, this pattern readily ties into recent work showing that trilobites and other animal clades with planktonic larval stages became a larger component of marine ecosystems during the Ordovician (Peterson 2005;Nützel et al 2006;Laibl et al 2023) and indicate that ecological turnover can be detected between high-resolution timescales, such as the transition between the Tremadocian and Floian.…”

Section: Homogenization Within the Fezouata Shale Formationsupporting

confidence: 64%

“…The homogenization of the Fezouata Shale Formation can be partially explained by examining the changes in the lifestyles of the trilobites in our dataset (Chatterton and Speyer 1989; Speyer and Chatterton 1989; Signor and Vermeij 1994; Hughes et al 2006; Fortey 2014; Laibl et al 2023), given the known colonization of the nektonic and planktonic realm by many animal groups throughout the late Cambrian and Early Ordovician (Servais et al 2010; Liu et al 2022). We find that 37% of the trilobite genera recovered from the subassemblages of the lower Fezouata Shale Formation belong to families known to have planktonic postembryonic larval stages (e.g., Asaphidae, Calymenidae, Nileidae), whereas 47% of the trilobite genera recovered from the upper Fezouata Shale Formation belong to families known to have planktonic postembryonic larval stages (e.g., Asaphidae, Calymenidae, Raphiophoridae).…”

Section: Discussionmentioning

confidence: 99%

“…We find that 37% of the trilobite genera recovered from the subassemblages of the lower Fezouata Shale Formation belong to families known to have planktonic postembryonic larval stages (e.g., Asaphidae, Calymenidae, Nileidae), whereas 47% of the trilobite genera recovered from the upper Fezouata Shale Formation belong to families known to have planktonic postembryonic larval stages (e.g., Asaphidae, Calymenidae, Raphiophoridae). In fact, three of the four most widely distributed trilobites (present in at least 50% subassemblages) of the upper Fezouata Shale Formation— Ampyx , Colpocoryphe , and Asaphellus —belong to families with planktonic larval stages (Laibl et al 2023). While dispersal influenced the movement and distribution of trilobites throughout the Ordovician (Chatterton and Speyer 1989; Perrier et al 2015; Lam et al 2018), the communities of the central Anti-Atlas region appear controlled by these dispersal forces to a lesser degree than many other neighboring regions (Saleh et al 2022a), as reflected in the slight percentage increase in taxa with planktonic larvae we observe between the Fezouata Shale sections (+10%).…”

Section: Discussionmentioning

confidence: 99%

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The Fezouata Shale Formation biota is typical for the high latitudes of the Early Ordovician—a quantitative approach

Richards,

Nanglu,

Ortega-Hernández

2024

Paleobiology

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The Fezouata Shale Formation has dramatically impacted our understanding of Early Ordovician marine ecosystems before the great Ordovician biodiversification event (GOBE), thanks to the abundance and quality of exceptionally preserved animals within it. Systematic work has noted that the shelly fossil subassemblages of the Fezouata Shale biota are typical of open-marine deposits from the Lower Ordovician, but no studies have tested the quantitative validity of this statement. We extracted 491 occurrences of recalcitrant fossil genera from the Paleobiology Database to reconstruct 31 subassemblages to explore the paleoecology of the Fezouata Shale and other contemporary, high-latitude (66°S–90°S) deposits from the Lower Ordovician (485.4–470 Ma) and test the interpretation that the Fezouata Shale biota is typical for an Ordovician open-marine environment. Sørensen's dissimilarity metrics and Wilcoxon tests indicate that the subassemblages of the Tremadocian-aged lower Fezouata Shale are approximately 20% more heterogenous than the Floian-aged upper Fezouata Shale. Dissimilarity metrics and visualization suggest that while the lower Fezouata and upper Fezouata share faunal components, the two sections have distinct faunas. We find that the faunal composition of the lower Fezouata Shale is comparable with other Tremadocian-aged subassemblages from high latitudes, suggesting that it is typical for an Early Ordovician open-marine environment. We also find differences in faunal composition between Tremadocian- and Floian-aged deposits. Our results corroborate previous field-based and qualitative systematic studies that concluded that the shelly assemblages of the Fezouata Shale are comparable with those of other Lower Ordovician deposits from high latitudes. This establishes the first quantitative baseline for examining the composition and variability within the assemblages of the Fezouata Shale and will be key to future studies attempting to discern the degree to which it can inform our understanding of marine ecosystems just before the start of the GOBE.

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Section: Homogenization Within the Fezouata Shale Formationsupporting

confidence: 64%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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The Fezouata Shale Formation biota is typical for the high latitudes of the Early Ordovician—a quantitative approach

Richards,

Nanglu,

Ortega-Hernández

2024

Paleobiology

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“…2006; Laibl et al . 2023) and the initial record of pelagic predators (Kröger et al . 2009; Whalen & Briggs 2018).…”

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confidence: 99%

Ecological novelty at the start of the Cambrian and Ordovician radiations of echinoderms

Novack‐Gottshall,

Purcell,

Sultan

et al. 2024

Palaeontology

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The Cambrian and Ordovician radiations marked the origins of all major echinoderm clades and established their Phanerozoic ecological blueprint. Recent claims of modest innovation of early echinoderms and other animals suggest constraints on novelty during the origins of phyla. Here, we document the life‐habit richness, body size, tiering, habitat usage, mobility, diet and foraging habits of 366 Cambrian–Ordovician echinoderm genera across a time‐scaled phylogeny to identify the timing and impact of novelty. Most early echinoderms were sedentary, filter‐feeding microbivores, and their body sizes, diets and modes of locomotion were largely unchanged through time, despite major volatility in taxonomic composition. Cambrian echinoderms lived close to the seafloor, with stylophorans first evolving semi‐infaunality. Many Ordovician echinoderms lived farther from the seafloor, with more complex filter‐feeding organs and tiering structure, often using other organisms as substrates. Mobile carnivores and mass‐feeders emerge then, too, across diverse asterozoans and echinozoans. Most of these novelties coincide with the origins of individual clades during the early and late Cambrian (Terreneuvian/Series 2 and Furongian), and 10–20 million years pass before most become ecologically important. Life‐habit evolution within most taxa involved new variations in these traits, with crinoids and asterozoans better able to shift strategies. The Ordovician radiation records more new variability in pre‐existing Cambrian life habits rather than radical re‐invention, with important novelties (like mobile carnivory and mass‐feeding, increased height off the seafloor, and biotic substrates) becoming ecologically more impactful. Taxa with these strategies were those best able to capitalize on the newly heterogeneous Ordovician world.

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“…Ecological diversity in trilobites has been suggested to peak during the Ordovician (Fortey & Owens 1990). For example, several groups independently evolved planktic larvae towards the late Cambrian and early Ordovician (Chatterton & Speyer 1989; Laibl et al, 2023), trilobites are thought to have occupied a range of levels in the water column during the Ordovician (Esteve and López-Pachón, 2023; Fortey, 2014, 1985; McCormick and Fortey, 1998), and some species expanded into deeper and tropical environments (Hopkins, 2014). The shape of the cephalon would have played an important role for moving and feeding within the water column, under conditions very different to those encountered by benthic forms (e.g., Fortey 1985; Esteve and López-Pachón, 2023).…”

Section: Discussionmentioning

confidence: 99%

Distinct causes underlie double-peaked trilobite morphological disparity

Drage,

Pates

2024

Preprint

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Trilobite cephalic morphology impacted the autecology of individuals, and is critical for high- and low-level taxonomic assignments. Disparity in trilobite cephalon shape varied through time and was integral to the occupation of a diversity of ecological niches. To fully appreciate trilobite cephalic evolution, we must understand how this disparity varies, and what factors control cephalon morphometry. We explore the disparity of trilobite cephala through the Palaeozoic, and analyse the associations between cephalic morphometry and taxonomic assignment and geological Period, using a dataset of 983 2D trilobite cephalon outlines. Elliptical Fourier transformation visualised as a Principal Components Analysis suggests significant differences in morphospace occupation for order and Period groups, and comparisons of disparity measures also suggest significantly different disparities between the groups. Trilobite cephalic disparity peaks in the Ordovician and Devonian. The Cambrian–Ordovician expansion of morphospace occupation appears a result of radiation to new niches, and thus all trilobite orders were established by the late Ordovician. In comparison, the morphospace expansion from the Silurian to Devonian seems solely a result of within-niche diversification rather than novel niche occupation. However, analyses interrogating the regions of morphospace occupied, including centroid distances, average pairwise shape comparisons and Linear Discriminant Analysis demonstrate that, except for the order Harpida and the Cambrian and Ordovician Periods, order and geological Period could not be robustly predicted for an unknown trilobite. Further, Kmeans clustering analyses suggest the total dataset naturally subdivides into only seven groups that do not correspond with taxonomic orders, though Kmeans clusters do decrease in number through the Palaeozoic, aligning with findings of decreasing disparity.

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Drifting with trilobites: The invasion of early post-embryonic trilobite stages to the pelagic realm

Cited by 17 publications

References 91 publications

The Fezouata Shale Formation biota is typical for the high latitudes of the Early Ordovician—a quantitative approach

The Fezouata Shale Formation biota is typical for the high latitudes of the Early Ordovician—a quantitative approach

Ecological novelty at the start of the Cambrian and Ordovician radiations of echinoderms

Distinct causes underlie double-peaked trilobite morphological disparity

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