More Like this

1. Revisions to the fossil sporophyte record of Marsilea

   https://doi.org/10.2478/acpa-2019-0005  

   Hermsen, Elizabeth J. ( June 2019 , Acta Palaeobotanica)

   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 campanicamore »(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.« less
2. Late Cretaceous angiosperm woods from the McRae Formation, south-central New Mexico, USA: Part 2

   https://doi.org/DOI: 10.1086/695503  

   Estrada-Ruiz, E. ; Wheeler, E.A. ; Upchurch, G.R. ; Mack, G.H. ( January 2018 , International Journal of Plant Sciences)

   Premise of research. Over the past 3 decades, angiosperm woods have been reported from the Campanian to the Maastrichtian of southern Laramidia, including Coahuila and Chihuahua, Mexico; Big Bend National Park, Texas; and the San Juan Basin, New Mexico. Recent investigations of the upper Campanian (76.5 to >72.5 Ma) Jose Creek Member of the McRae Formation, south-central New Mexico, indicate an abundance of well-preserved silicified woods, representing one of the most diverse Cretaceous wood floras in the world. In this report, we describe four new angiosperm wood types. Methodology. The fossil woods described here were collected from the upper Campanian of south-central New Mexico, along the northeastern flank of the Caballo Mountains and in the adjacent Cutter Sag, and were studied using thin sections. The potential affinities of these McRae woods were determined by comparison with fossil and extant woods. Pivotal results. The woods reported here comprise one magnoliid and three eudicots with varying levels of comparability to extant taxa. Laurinoxylon rennerae sp. nov. belongs to Lauraceae and has a combination of features found in multiple extant genera variously referred to as Cinnamomeae Nees, Laureae Maout & Decaisne, or Lauroideae Burnett/core Lauraceae. Turneroxylon newmexicoense gen. et sp. nov. is amore »eudicot with many similarities to Dilleniaceae but differs in having narrower rays. Mcraeoxylon waddellii gen. et sp. nov. has a suite of features seen in several families of Malpighiales, Myrtales, and Oxalidales. McRae angiosperm wood type 1 has a suite of features found in genera of Dilleniales, Ericales, and Malpighiales. Conclusions. All wood types, with the exception of M. waddellii, have minimum axis diameters of 110 cm (12–50 cm), indicating that they represent trees. This reinforces previous evidence for the presence of small to large angiosperm trees in the Jose Creek Member and underscores the importance of woody angiosperms in vegetation of the southern Western Interior during the Campanian-Maastrichtian.« less
3. Fossil evidence from South America for the diversification of Cunoniaceae by the earliest Palaeocene

   https://doi.org/10.1093/aob/mcaa154  

   Jud, Nathan A ; Gandolfo, Maria A ( August 2020 , Annals of Botany)

   null (Ed.)

   Abstract Background and Aims Cunoniaceae are woody plants with a distribution that suggests a complex history of Gondwanan vicariance, long-distance dispersal, diversification and extinction. Only four out of ~27 genera in Cunoniaceae are native to South America today, but the discovery of extinct species from Argentine Patagonia is providing new information about the history of this family in South America. Methods We describe fossil flowers collected from early Danian (early Palaeocene, ~64 Mya) deposits of the Salamanca Formation. We compare them with similar flowers from extant and extinct species using published literature and herbarium specimens. We used simultaneous analysis of morphology and available chloroplast DNA sequences (trnL–F, rbcL, matK, trnH–psbA) to determine the probable relationship of these fossils to living Cunoniaceae and the co-occurring fossil species Lacinipetalum spectabilum. Key Results Cunoniantha bicarpellata gen. et sp. nov. is the second species of Cunoniaceae to be recognized among the flowers preserved in the Salamanca Formation. Cunoniantha flowers are pentamerous and complete, the anthers contain in situ pollen, and the gynoecium is bicarpellate and syncarpous with two free styles. Phylogenetic analysis indicates that Cunoniantha belongs to crown-group Cunoniaceae among the core Cunoniaceae clade, although it does not have obvious affinity with any tribe.more »Lacinipetalum spectabilum, also from the Salamanca Formation, belongs to the Cunoniaceae crown group as well, but close to tribe Schizomerieae. Conclusions Our findings highlight the importance of West Gondwana in the evolution of Cunoniaceae during the early Palaeogene. The co-occurrence of C. bicarpellata and L. spectabilum, belonging to different clades within Cunoniaceae, indicates that the diversification of crown-group Cunoniaceae was under way by 64 Mya.« less
4. Hyainailourine and teratodontine cranial material from the late Eocene of Egypt and the application of parsimony and Bayesian methods to the phylogeny and biogeography of Hyaenodonta (Placentalia, Mammalia)

   https://doi.org/10.7717/peerj.2639  

   Borths, Matthew R. ; Holroyd, Patricia A. ; Seiffert, Erik R. ( November 2016 , PeerJ)

   Hyaenodonta is a diverse, extinct group of carnivorous mammals that included weasel- to rhinoceros-sized species. The oldest-known hyaenodont fossils are from the middle Paleocene of North Africa and the antiquity of the group in Afro-Arabia led to the hypothesis that it originated there and dispersed to Asia, Europe, and North America. Here we describe two new hyaenodont species based on the oldest hyaenodont cranial specimens known from Afro-Arabia. The material was collected from the latest Eocene Locality 41 (L-41, ∼34 Ma) in the Fayum Depression, Egypt.Akhnatenavus nefertiticyonsp. nov. has specialized, hypercarnivorous molars and an elongate cranial vault. InA. nefertiticyonthe tallest, piercing cusp on M¹–M²is the paracone.Brychotherium ephalmosgen. et sp. nov. has more generalized molars that retain the metacone and complex talonids. InB. ephalmosthe tallest, piercing cusp on M¹–M²is the metacone. We incorporate this new material into a series of phylogenetic analyses using a character-taxon matrix that includes novel dental, cranial, and postcranial characters, and samples extensively from the global record of the group. The phylogenetic analysis includes the first application of Bayesian methods to hyaenodont relationships.B. ephalmosis consistently placed within Teratodontinae, an Afro-Arabian clade with several generalist and hypercarnivorous forms, andAkhnatenavusis consistently recovered in Hyainailourinae as part of an Afro-Arabianmore »radiation. The phylogenetic results suggest that hypercarnivory evolved independently three times within Hyaenodonta: in Teratodontinae, in Hyainailourinae, and in Hyaenodontinae. Teratodontines are consistently placed in a close relationship with Hyainailouridae (Hyainailourinae + Apterodontinae) to the exclusion of “proviverrines,” hyaenodontines, and several North American clades, and we propose that the superfamily Hyainailouroidea be used to describe this relationship. Using the topologies recovered from each phylogenetic method, we reconstructed the biogeographic history of Hyaenodonta using parsimony optimization (PO), likelihood optimization (LO), and Bayesian Binary Markov chain Monte Carlo (MCMC) to examine support for the Afro-Arabian origin of Hyaenodonta. Across all analyses, we found that Hyaenodonta most likely originated in Europe, rather than Afro-Arabia. The clade is estimated by tip-dating analysis to have undergone a rapid radiation in the Late Cretaceous and Paleocene; a radiation currently not documented by fossil evidence. During the Paleocene, lineages are reconstructed as dispersing to Asia, Afro-Arabia, and North America. The place of origin of Hyainailouroidea is likely Afro-Arabia according to the Bayesian topologies but it is ambiguous using parsimony. All topologies support the constituent clades–Hyainailourinae, Apterodontinae, and Teratodontinae–as Afro-Arabian and tip-dating estimates that each clade is established in Afro-Arabia by the middle Eocene.

   « less
5. Canopy Structure in Late Cretaceous and Paleocene Forests as Reconstructed from Carbon Isotope Analyses of Fossil Leaves

   Graham, Heather ; Herrera, Fabiany ; Jaramillo, Carlos ; Wing, Scott ; Freeman, Katherine ( January 2019 , Geology)

   While modern forests have their origin in the diversification and expansion of angiosperms in the late Cretaceous and early Cenozoic, it is unclear if the rise of closed-canopy tropical rainforests preceded or followed the end-Cretaceous extinction. The “canopy effect” is a strong vertical gradients in the carbon isotope (δ13C) composition of leaves in modern closed-canopy forests that could serve as a proxy signature for canopy structure in ancient forests. To test this, we report measurements of the carbon isotope composition of nearly 200 fossil angiosperm leaves from two localities in the Paleocene Cerrejón Formation and one locality in the Maastrichtian Guaduas Formation. Leaves from one Cerrejón fossil assemblage deposited in a small fluvial channel exhibited a 6.3‰ range in δ13C, consistent with a closed-canopy forest. Carbon isotope values from lacustrine sediments in the Cerrejón Fm. had a range of 3.3‰, consistent with vegetation along a lake edge. An even narrower range of δ13C values (2.7‰) was observed for a leaf assemblage recovered from the Cretaceous Guaduas Fm., and suggests vegetation with an open canopy structure. Carbon isotope fractionation by late Cretaceous and early Paleogene leaves was in all cases similar to modern relatives, consistent with estimates of low atmospheric CO2more »during this time period. This study confirms other lines of evidence suggesting closed-canopy forests in tropical South America existed by the late Paleocene, and fails to find isotopic evidence for a closed-canopy forest in the Cretaceous.« less