Evolution: Ancient Fossilized Amoebae Find Their Home in the Tree

Porter, Susannah M.; Riedman, Leigh Anne

doi:10.1016/j.cub.2019.02.003

Cited by 15 publications

(34 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The scale microfossils described here are also similar in size and shape (if not composition) to some scales produced by members of the Amoebozoa and Rhizaria (Ogden & Hedley, 1980;Figure 4.12-4.14). In fact (and discussed in detail below), vase-shaped microfossils, a group allied with the arcellinid Amoebozoa (Porter & Knoll, 2000;Porter & Riedman, 2019), occur in all of the samples as the scales presented here (Knoll & Calder, 1983;Porter & Knoll, 2000;Horodyski, 1993;Porter et al, 2003;Dehler, 2014;Riedman et al, 2018;Figure 2.15) as well as in the Visingsö Group of Sweden (Martí Mus & Moczydłowska, 2000;Moczydłowska et al, 2017).…”

Section: Biological Affinitiesmentioning

confidence: 52%

“…Alternatively, this cooccurrence could reflect a biological signal indicating that these apatitic scale microfossils derive from individuals within the VSM group (e.g., the VSM Melicerion poikilon has been suggested to have borne scales, Porter & Knoll, 2000;Porter et al, 2003). As mentioned above, VSMs have been robustly allied with the Arcellinida, a major group of test (shell) forming single-celled eukaryotes (Porter & Riedman, 2019). Intriguingly, although no known modern arcellinid forms organic scales that are coated and imbued with apatite, some are known to produce tests from organic or mineralized scales, some taxa coat their scales or exogenous particles with resistant organic material or with biosilica (Anderson, 1987), and one taxon (Cryptodifflugia) has been reported to coat the inside of its organic test with calcium phosphate (Hedley et al, 1977).…”

Section: Association With Vase-shaped Microfossilsmentioning

confidence: 99%

See 1 more Smart Citation

Phosphatic scales in vase‐shaped microfossil assemblages from Death Valley, Grand Canyon, Tasmania, and Svalbard

2021

Self Cite

View full text Add to dashboard Cite

Although biomineralized skeletal elements dominate the Phanerozoic fossil record, they did not become common until ~550-520 Ma when independent acquisitions of biomineralization appeared in multiple lineages of animals and a few protists (singlecelled eukaryotes). Evidence of biomineralization preceding the late Ediacaran is spotty aside from the apatitic scale microfossils of the ~811 Ma Fifteenmile Group, northwestern Canada. Here, we describe scale-shaped microfossils from four vase-shaped microfossil (VSM)-bearing units of later Tonian age: the Togari Group of Tasmania, Chuar and Pahrump groups of southwestern United States, and the Roaldtoppen Group of Svalbard. These scale-shaped microfossils consist of thin, ~13 micron-long plates typically surrounded by a 1-3 micron-thick colorless envelope; they are found singly and in heterotypic and monotypic clusters of a few to >20 specimens. Raman spectroscopy and confocal laser scanning microscopy indicate these microfossils are composed of apatite and kerogen, just as is seen in the Fifteenmile Group scale microfossils. Despite compositional similarity, however, these scales are probably not homologous, representing instead, an independent acquisition of apatite mineralization. We propose that these apatite-kerogen scale-shaped microfossils are skeletal elements of a protistan cell. In particular, their consistent co-occurrence with VSMs, and similarities with scales of arcellinid testate amoebae, a group to which the VSMs are thought to belong, suggest the possibility that these microfossils may be test-forming scales of ancient arcellinid testate amoebae. The apparent apatite biomineralization in both these microfossils and the Fifteenmile scales is unexpected given its exceedingly rare use in skeletons of modern protists. This modern absence is attributed to the extravagance of using a limiting nutrient in a structural element, but multiple occurrences of apatite biomineralization in the Tonian suggest that phosphorus was not a limiting nutrient for these organisms, a suggestion consistent with the idea that dissolved seawater phosphate concentrations may have been higher at this time.

show abstract

Section: Biological Affinitiesmentioning

confidence: 52%

Section: Association With Vase-shaped Microfossilsmentioning

confidence: 99%

Phosphatic scales in vase‐shaped microfossil assemblages from Death Valley, Grand Canyon, Tasmania, and Svalbard

2021

Self Cite

View full text Add to dashboard Cite

show abstract

“…Similar perforations are also found in walls of younger organic-walled eukaryotic microfossils (the vase-shaped microfossils, or VSMs) from the 780 to 740 Ma Chuar Group, Grand Canyon, Arizona, USA [30,31], which are also widely interpreted as the direct result of eukaryovory [9,29,[32][33][34]. These VSMs-and others from comparably aged assemblages ca 789-729 Ma [35,36]-are interpreted as representing the oldest fossil evidence for arcellinid testate amoebae [37,38], which are abundant and diverse in modern freshwater and soil habitats, where they are largely bacterivorous and eukaryovorous [39][40][41]. Therefore, the VSMs themselves-with or without perforations-also serve as evidence for bacterivory and eukaryovory by ca 789 Ma [9,30,33,34,37,38].…”

Section: The Earliest Evidence For Eukaryotic Predation 21 Palaeontological and Molecular Evidencementioning

confidence: 68%

“…Both fossil data and molecular clock estimates suggest an origin of the eukaryotic crown-group sometime between 2.0 and 1.0 Ga [14, 25,[48][49][50][51]129,130]. While total-group eukaryotic fossils likely extend back to the Paleoproterozoic Era (2.5-1.6 Ga), the oldest widely accepted crown-group royalsocietypublishing.org/journal/rsfs Interface Focus 10: 20200019 eukaryotic fossils date from ca 1.05 Ga [18,19,21] to ca 789-759 Ma [37,38]. Likewise, the oldest eukaryotic steranes date to ca 820 to 720 Ma [60].…”

Section: Scenarios For Last Eukaryotic Common Ancestormentioning

confidence: 99%

The origin of phagocytosis in Earth history

Mills

2020

Interface Focus.

View full text Add to dashboard Cite

Phagocytosis, or ‘cell eating’, is a eukaryote-specific process where particulate matter is engulfed via invaginations of the plasma membrane. The origin of phagocytosis has been central to discussions on eukaryogenesis for decades, where it is argued as being either a prerequisite for, or consequence of, the acquisition of the ancestral mitochondrion. Recently, genomic and cytological evidence has increasingly supported the view that the pre-mitochondrial host cell—a bona fide archaeon branching within the ‘Asgard’ archaea—was incapable of phagocytosis and used alternative mechanisms to incorporate the alphaproteobacterial ancestor of mitochondria. Indeed, the diversity and variability of proteins associated with phagosomes across the eukaryotic tree suggest that phagocytosis, as seen in a variety of extant eukaryotes, may have evolved independently several times within the eukaryotic crown-group. Since phagocytosis is critical to the functioning of modern marine food webs (without it, there would be no microbial loop or animal life), multiple late origins of phagocytosis could help explain why many of the ecological and evolutionary innovations of the Neoproterozoic Era (e.g. the advent of eukaryotic biomineralization, the ‘Rise of Algae’ and the origin of animals) happened when they did.

show abstract

“…Cocroft and Rodriguez [7] showed us communication via substrate-borne vibration within a species is widespread and ancient, but also that signals and cues from these vibrations could be used in just as many contexts as other animals used airborne sound or chemical communication. Hill [8] reviewed the literature to reveal the commonalities across animal taxa and found the same basic mechanisms for intentionally producing these vibrations were present in systems, from tiny insects to elephants. The authors [4] discussed the potential for use of chemical signals that are released when the plant is damaged.…”

Section: Current Biologymentioning

confidence: 99%