scholarly journals Revisions to the fossil sporophyte record of Marsilea

2019 ◽  
Vol 59 (1) ◽  
pp. 27-50 ◽  
Author(s):  
Elizabeth J. Hermsen
Keyword(s):  
Fossil Record ◽  
Upper Cretaceous ◽  
Critical Evaluation ◽  
Green River Formation ◽  
Aquatic Angiosperm ◽  
Green River ◽  
Fossil Species ◽  
Architectural Features ◽  
Distinct Genus ◽  
Taxonomic Changes

Abstract The fossil record of Marsilea is challenging to assess, due in part to unreliable reports and conflicting opinions regarding the proper application of the names Marsilea and Marsileaceaephyllum to fossil leaves and leaflets similar to those of modern Marsilea. Specimens examined for this study include material assigned to Marsileaceaephyllum johnhallii, purportedly the oldest fossil record of a Marsilea-like sporophyte from the Lower Cretaceous of the Dakota Formation, Kansas, U.S.A.; leaves and leaf whorls of the extinct aquatic angiosperm Fortuna from several Late Cretaceous and Paleocene localities in western North America; and leaves and leaflets resembling Marsilea from the Eocene Green River Formation, Colorado and Utah, U.S.A. Literature on the fossil record of Marsilea was also reviewed. As a result, several taxonomic changes are proposed. Marsileaceaephyllum johnhallii is reinterpreted as an aquatic angiosperm that shares some architectural features with the genus Fortuna, although Marsileaceaephyllum is here maintained as a distinct genus with an emended diagnosis; under this reinterpretation, the name Marsileaceaephyllum can no longer be applied to sporophyte organs with affinities to Marsileaceae. Three valid fossil Marsilea species are recognized on the basis of sporophyte material that includes characteristic quadrifoliolate leaves and reticulate-veined leaflets: Marsilea campanica (J. Kvaček & Herman) Hermsen, comb. nov., from the Upper Cretaceous Grünbach Formation, Austria; Marsilea mascogos Estrada-Ruiz et al., from the Upper Cretaceous Olmos Formation, Mexico; and Marsilea sprungerorum Hermsen, sp. nov., from the Eocene Green River Formation, U.S.A. The species are distinguished from one another based on leaflet dimensions. Leaves from the Eocene Wasatch Formation, U.S.A., are transferred from Marsileaceaephyllum back to Marsilea, although not assigned to a fossil species. Finally, an occurrence of Marsilea from the Oligocene of Ethiopia is reassigned to Salvinia. A critical evaluation of the fossil record of Marsilea thus indicates that (1) the oldest fossil marsileaceous sporophytes bearing Marsilea-like leaves are from the Campanian; (2) only four credible records of sporophyte material attributable to Marsilea are known; and (3) the oldest dispersed Marsilea spores are known from the Oligocene.

scholarly journals An Exceptionally Preserved Specimen From the Green River Formation Elucidates Complex Phenotypic Evolution in Gruiformes and Charadriiformes

2020 ◽  
Vol 8 ◽  
Author(s):  
Grace Musser ◽  
Julia A. Clarke
Keyword(s):  
Fossil Record ◽  
Phylogenetic Analyses ◽  
Divergence Time ◽  
Axial Skeleton ◽  
Green River Formation ◽  
New Taxon ◽  
Early Eocene ◽  
Phenotypic Evolution ◽  
Green River ◽  
Partial Skeleton

The stem lineage relationships and early phenotypic evolution of Charadriiformes (shorebirds) and Gruiformes (rails, cranes, and allies) remain unresolved. It is still debated whether these clades are sister-taxa. New phylogenetic analyses incorporating Paleogene fossils have the potential to reveal the evolutionary connections of these two speciose and evolutionarily critical neoavian subclades. Although Gruiformes have a rich Paleogene fossil record, most of these fossils have not been robustly placed. The Paleogene fossil record of Charadriiformes is scarce and largely consists of fragmentary single elements. Only one proposed Eocene charadriiform-like taxon, Scandiavis mikkelseni of Denmark, is represented by a partial skeleton. Here, we describe a new species from the early Eocene Green River Formation of North America comprising a partial skeleton and feather remains. Because the skeleton lacks the pectoral girdle and forelimbs as in S. mikkelseni, only features of the skull, axial skeleton, and hind limb are available to resolve the phylogenetic placement of this taxon. These anatomical subregions initially showed features seen in Charadriiformes and Gruiformes. To assess placement of this taxon, we use a matrix consisting of 693 morphological characters and 60 taxa, including S. mikkelseni and the oldest known charadriiform taxa represented by single elements. These more fragmentary records comprise two distal humeri from the earliest Eocene Naranbulag Formation of Mongolia and the early Eocene Nanjemoy Formation of Virginia. Our phylogenetic analyses recover the new taxon and S. mikkelseni alternatively as a charadriiform or as a stem-gruiform; placement is contingent upon enforced relationships for major neoavian subclades recovered by recent molecular-based phylogenies. Specifically, when constraint trees based on results that do not recover Charadriiformes and Gruiformes as sister-taxa are used, the new taxon and S. mikkelseni are recovered within stem Gruiformes. Both Paleogene fossil humeri are consistently recovered within crown Charadriiformes. If placement of these humeri or the new taxon as charadriiforms are correct, this may indicate that recent divergence time analyses have underestimated the crown age of another major crown avian subclade; however, more complete sampling of these taxa is necessary, especially of more complete specimens with pectoral elements.

scholarly journals Systematics and phylogeny of the Zygodactylidae (Aves, Neognathae) with description of a new species from the early Eocene of Wyoming, USA

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4950 ◽  
Author(s):  
N. Adam Smith ◽  
Aj M. DeBee ◽  
Julia A. Clarke
Keyword(s):  
New Species ◽  
Fossil Record ◽  
Species Level ◽  
Green River Formation ◽  
Early Eocene ◽  
Green River ◽  
Exceptional Preservation ◽  
Taxonomic History ◽  
Ancestral States ◽  
A New Species

Zygodactylidae are an extinct lineage of perching birds characterized by distinct morphologies of the foot and wing elements. Although the clade has a complex taxonomic history, current hypotheses place Zygodactylidae as the sister taxon to Passeriformes (i.e., songbirds). Given the rather sparse fossil record of early passeriforms, the description of zygodactylid taxa is important for inferring potentially ancestral states in the largest radiation of living birds (i.e., the ∼6,000 species of extant passeriforms). Despite the exceptional preservation of many specimens and considerable species diversity in Zygodactylidae, the relationships among species have not been previously evaluated in a phylogenetic context. Herein, we review the fossil record of Zygodactylidae from North America and describe five new well-preserved fossils from the early Eocene Green River Formation of Wyoming. Two specimens are identified as representing a new species and the first records of the taxonZygodactylusoutside Europe. Anatomical comparisons with previously named taxa and the results of phylogenetic analysis including newly described specimens and previously named zygodactylid taxa provide the first hypothesis of the species-level relationships among zygodactylids. The monophyly of Zygodactylidae is supported in these new analyses. However, the monophyly ofPrimozygodactylusand the taxonomic distinction betweenZygodactylusandEozygodactylusremain unresolved and would likely benefit from the description of additional specimens.

The same picture through different lenses: quantifying the effects of two preservation pathways on Green River Formation insects

Paleobiology ◽  
2017 ◽  
Vol 43 (2) ◽  
pp. 224-247 ◽  
Author(s):  
Evan P. Anderson ◽  
Dena M. Smith
Keyword(s):  
Organic Matter ◽  
Iron Oxide ◽  
Fossil Record ◽  
Extended Period ◽  
Early Diagenesis ◽  
The Body ◽  
Green River Formation ◽  
Body Parts ◽  
Green River ◽  
Recalcitrant Organic Matter

AbstractInsects in the fossil record are generally preserved in lacustrine shales or in amber. For those in lacustrine shales, preservation is usually via keroginization or mineralization. Given the extended period of microbial decay required to generate ions for mineralization, there is a predicted inherent bias toward lower preservation quality for this pathway by most taphonomic indices compared with keroginization. This study tests this hypothesis by comparing multiple measures of preservation quality between sites with similar sedimentology in the Eocene Green River Formation of Colorado. Here, insects are either mineralized in iron oxides (likely after pyrite) at the Paleoburn site or keroginized at the Anvil Points site.Generally, the prediction that keroginization preserves soft-bodied fossils with higher preservational quality than mineralization is affirmed, but with some caveats. Beetles, known for their robust cuticles, are proportionately more abundant at the Paleoburn site, but eight of the nine orders recorded are shared between sites. As predicted, insects show lower preservation fidelity at the Paleoburn site, but they also show higher degrees of disarticulation. This second bias should be acquired primarily during the biostratinomy stage, and not early diagenesis. Nonetheless, higher-energy biostratinomic conditions may be compatible with taphonomic conditions that promote mineralization over keroginization.Comparing the inherent taphonomic bias of different preservation pathways is often difficult, since fossil deposits may be preserved millions of years or thousands of kilometers apart. By studying two different preservation pathways of insects within the same formation, we can affirm that keroginization does indeed preserve recalcitrant organic matter with higher quality than pyritization or iron-oxide mineralization. Additionally, some guidelines can be proposed concerning the body parts and taxa that can be compared, and for what purpose, when contrasting mineralized and keroginized soft-bodied deposits.

First fossil record of the genus Reissa Evenhuis & Báez (Diptera: Mythicomyiidae: Mythicomyiinae) from the Eocene Green River Formation of North America, and discussion of biogeographical implications

2019 ◽  
Vol 2 (3) ◽  
pp. 223-228
Author(s):  
NEAL L. EVENHUIS
Keyword(s):  
New Species ◽  
North America ◽  
Fossil Record ◽  
New World ◽  
First Record ◽  
Green River Formation ◽  
Green River ◽  
Fossil Specimen ◽  
The Family ◽  
Fossil Genus

The genus Reissa Evenhuis & Báez in Greathead & Evenhuis (2001) was originally described based on a short series of extant specimens from the island of Tenerife in the Canary Islands. No further species of the genus have been discovered since. A related fossil genus (Riga Evenhuis) was described from Eocene Rovno amber (Evenhuis, 2013) and has some characters in common with the fossil specimen but differs in thoracic and antennal features. The new species described and illustrated here is represented by a single compression fossil of the new species Reissa kohlsi sp. nov. from the Parachute Creek member of the Green River Formation of Wyoming/Utah/Colorado, USA, the site of which dates from 51.2–48.7 my (Smith et al., 2008). It marks the first fossil record of the genus and its first record from the New World, and the first fossil record of the family Mythicomyiidae from North America. The family was previously known in the New World fossil record from the Miocene Dominican amber (cf. Evenhuis, 2013), including two representatives from the Mythicomyiinae (Mythicomyia dominicana Evenhuis, 2002 and Pieza dominicana Evenhuis, 2002).

scholarly journals The Oldest Representative of the Rove Beetle Tribe Pinophilini (Coleoptera: Staphylinidae: Paederinae), from Upper Cretaceous Burmese Amber

Insects ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 174
Author(s):  
Josh Jenkins Shaw ◽  
Bo Wang ◽  
Ming Bai ◽  
Dagmara Żyła
Keyword(s):  
Upper Cretaceous ◽  
Phylogenetic Analyses ◽  
Green River Formation ◽  
Morphological Data ◽  
Green River ◽  
Burmese Amber ◽  
Rove Beetle ◽  
Insight Into

The recently reviewed subtribe Procirrina comprises eight extant genera with a predominately (sub)tropical distribution. Previous phylogenies consistently recover the tribe Pinophilini of the subfamily Paederinae monophyletic. No fossils of the tribe have been described, although compression fossils are known from the Cenozoic Green River Formation (50.3–46.2 Ma) as well as inclusions from the Miocene Dominican (20.43–13.65 Ma) and Mexican (20–15 Ma) ambers. Here we describe †Cretoprocirrus trichotos Jenkins Shaw and Żyła gen. et sp. n., the oldest fossil representative of the tribe Pinophilini, from Upper Cretaceous Burmese amber (ca. 99 Ma). Phylogenetic analyses of morphological data allow its unambiguous placement in the subtribe Procirrina. †Cretoprocirrus trichotos is the second genus of Paederinae described from Burmese amber and provides an important insight into the evolution of the subfamily.

Exceptionally preserved fossil insect ears from the Eocene Green River Formation of Colorado

2012 ◽  
Vol 86 (1) ◽  
pp. 19-24 ◽  
Author(s):  
Roy E. Plotnick ◽  
Dena M. Smith
Keyword(s):  
Fossil Record ◽  
The Body ◽  
Green River Formation ◽  
Green River ◽  
Fossil Insect ◽  
Multiple Regions ◽  
Intraspecific Communication

Tympanal ears in insects are important for both intraspecific communication and for the detection of nocturnal predators. Ears are thought, based on modern forms, to have originated independently multiple times within insects and can be found on multiple regions of the body. Here we describe and document the exceptionally well preserved tympanal ears found in crickets and katydids from the Eocene Green River Formation of Colorado, which are virtually identical to those seen in modern representatives of these groups. These specimens are among the best preserved insect ears in the fossil record and establish the presence of ears in two major clades of Orthoptera 50 million years ago. Also discussed and evaluated are previously described insect ears from the Mesozoic and the implications of the findings of the present study for studying the evolution of ears within insects.

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