scholarly journals Deep time diversity of metatherian mammals: implications for evolutionary history and fossil-record quality

Paleobiology ◽  
2018 ◽  
Vol 44 (2) ◽  
pp. 171-198 ◽  
Author(s):  
C. Verity Bennett ◽  
Paul Upchurch ◽  
Francisco J. Goin ◽  
Anjali Goswami
Keyword(s):  
Fossil Record ◽  
Late Eocene ◽  
Didelphis Virginiana ◽  
Early Miocene ◽  
South American ◽  
Data Set ◽  
Deep Time ◽  
The North ◽  
Time Diversity ◽  
Diversity Estimates

AbstractDespite a global fossil record, Metatheria are now largely restricted to Australasia and South America. Most metatherian paleodiversity studies to date are limited to particular subclades, time intervals, and/or regions, and few consider uneven sampling. Here, we present a comprehensive new data set on metatherian fossil occurrences (Barremian to end Pliocene). These data are analyzed using standard rarefaction and shareholder quorum subsampling (including a new protocol for handling Lagerstätte-like localities).Global metatherian diversity was lowest during the Cretaceous, and increased sharply in the Paleocene, when the South American record begins. Global and South American diversity rose in the early Eocene then fell in the late Eocene, in contrast to the North American pattern. In the Oligocene, diversity declined in the Americas, but this was more than offset by Oligocene radiations in Australia. Diversity continued to decrease in Laurasia, with final representatives in North America (excluding the later entry ofDidelphis virginiana) and Europe in the early Miocene, and Asia in the middle Miocene. Global metatherian diversity appears to have peaked in the early Miocene, especially in Australia. Following a trough in the late Miocene, the Pliocene saw another increase in global diversity. By this time, metatherian biogeographic distribution had essentially contracted to that of today.Comparison of the raw and sampling-corrected diversity estimates, coupled with evaluation of “coverage” and number of prolific sites, demonstrates that the metatherian fossil record is spatially and temporally extremely patchy. Therefore, assessments of macroevolutionary patterns based on the raw fossil record (as in most previous studies) are inadvisable.

The southernmost fossil record of Squamates

2017 ◽  
Vol 38 (1) ◽  
pp. 15-30 ◽  
Author(s):  
Adriana Albino ◽  
Santiago Brizuela ◽  
Sergio Vizcaíno
Keyword(s):  
South America ◽  
Fossil Record ◽  
Early Miocene ◽  
Substantial Part ◽  
South American ◽  
Santa Cruz ◽  
Origin And Evolution ◽  
Present Distribution ◽  
First Time

Squamates form a substantial part of the present-day South American herpetofauna, and their fossils constitute an indispensable evidence for understanding the origin and evolution of the main taxa. Squamates are relatively common in Miocene localities of Patagonia, especially in levels of the late early Miocene Santa Cruz Formation. In this contribution, remains of the three species of the extinct iguanidErichosaurusAmeghino 1899 (E. diminutus,E. bombimaxillaandE. debilis) are redescribed, and new squamate specimens are reported for first time. The genusErichosaurusis considered invalid.Erichosaurus debilis,E. diminutusand a new specimen are recognized as indeterminate species of the extant polichrotinePristidactylus, whereasE. bombimaxillaremains as an indeterminate iguanid. Snakes are represented by an indeterminate colubrid. All these specimens, together with a tupinambine teiid previously described for the same formation, represent the southernmost fossil record of squamates in South America and indicate the occurrence of the iguanidPristidactylus, the teiidTupinambisand the colubrid snakes south to their present distribution as back as during the early Miocene.

New turtles (Chelonia) from the late Eocene through late Miocene of the Panama Canal Basin

2012 ◽  
Vol 86 (3) ◽  
pp. 539-557 ◽  
Author(s):  
Edwin Cadena ◽  
Jason R. Bourque ◽  
Aldo F. Rincon ◽  
Jonathan I. Bloch ◽  
Carlos A. Jaramillo ◽  
...  
Keyword(s):  
Late Miocene ◽  
Late Eocene ◽  
Panama Canal ◽  
Early Miocene ◽  
South American ◽  
Early Oligocene ◽  
Isthmus Of Panama ◽  
Early Arrival ◽  
The Tropics ◽  
First Contact

Four distinct fossil turtle assemblages (Chelonia) are recognized from the Panama Canal Basin. The oldest, from the late Eocene–early Oligocene Gatuncillo Formation, is dominated by podocnemidid pleurodires. The early Miocene Culebra Formation includes both podocnemidids and trionychids. The early to middle Miocene Cucaracha Formation includes taxa classified in Geoemydidae (including Rhinoclemmys panamaensis n. sp.), Kinosternidae (represented by Staurotypus moschus n. sp.), large testudinids, trionychids, and podocnemidids, and finally, the late Miocene Gatun Formation records cheloniid sea turtles. These fossils include the oldest known representatives of Rhinoclemmys, the oldest record of kinosternids in Central America with a more extensive southern paleodistribution for Staurotypus and staurotypines in general, early occurrences of giant tortoises in the Neotropics, the oldest occurrence of soft-shell turtles in the tropics, the oldest late Eocene–early Oligocene Neotropical occurrences of podocnemidids. The Panamanian fossil turtles represent clades that are primarily endemic to North America, showing their very early arrival into the Neotropics prior to the complete emergence of the Isthmus of Panama, as well as their first contact with Caribbean-South American pleurodires by the early Miocene.

scholarly journals Miocene sepiids (Cephalopoda, Coleoidea) from Australia

Fossil Record ◽  
2017 ◽  
Vol 20 (2) ◽  
pp. 159-172 ◽  
Author(s):  
Martin Košt'ák ◽  
Andrej Ruman ◽  
Ján Schlögl ◽  
Natalia Hudáčková ◽  
Dirk Fuchs ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Fossil Record ◽  
Middle Miocene ◽  
Late Eocene ◽  
Early Miocene ◽  
Type Ii ◽  
Late Oligocene ◽  
Biogeographical Distribution ◽  
Stem Lineage ◽  
Migratory Route

Abstract. Two sepiid genera, Notosepia Chapman, 1915, and Sepia Linnaeus, 1758, are described from the Neogene deposits of Australia. A new and unique record of the middle Miocene Sepia sp. is reported from southern Australia. Based on similarities to contemporaneous sepiids, the new sepiid cuttlebone described herein belongs to the genus Sepia. Notosepia cliftonensis is suggested herein to be a descendant of the archaeosepiid stem lineage. Microstructures (lamella-fibrillar nacre is the nacre Type II of septa and pillar prismatic layers) of the excellently preserved cuttlebone of Sepia sp. display a modern character of the phragmocone, fully comparable to the recent taxa. The stratigraphically well-calibrated (based on foraminifera) cuttlebone represents the first unambiguous fossil record of the genus Sepia from the Southern Hemisphere. It significantly extends the biogeographical distribution of modern sepiids in the Miocene and suggests the existence of a sepiid eastward migratory route. Moreover, the presence of both conservative- and modern-type cuttlebones suggests a dual colonisation of Australian waters: the first (archaeosepiid) during the late Eocene–late Oligocene and the second (sepiid) during the early Miocene.

African origin of caviomorph rodents is indicated by incisor enamel microstructure

Paleobiology ◽  
1994 ◽  
Vol 20 (1) ◽  
pp. 5-13 ◽  
Author(s):  
Thomas Martin
Keyword(s):  
North American ◽  
Late Eocene ◽  
South American ◽  
Late Oligocene ◽  
African Origin ◽  
Enamel Microstructure ◽  
The North ◽  
Early Oligocene ◽  
Caviomorph Rodents

The same three subtypes of derived multiserial Hunter-Schreger bands are found in the incisor enamel of African phiomorph rodents from the late Eocene-early Oligocene and the oldest South American Caviomorpha from the Deseadan (late Oligocene). The synapomorphies contained therein, especially arrangement and orientation of interprismatic matrix, make an African origin of the Caviomorpha very probable. A North American origin of the Caviomorpha is thus rejected, as only primitive pauciserial Hunter-Schreger bands have been observed in possible ischyromyoid caviomorph ancestors. A multiserial Schmelzmuster apparently never evolved in the North American rodent fauna.

scholarly journals A critical revision of the fossil record, stratigraphy and diversity of the Neogene seal genus Monotherium (Carnivora, Phocidae)

2018 ◽  
Vol 5 (5) ◽  
pp. 171669 ◽  
Author(s):  
Leonard Dewaele ◽  
Olivier Lambert ◽  
Stephen Louwye
Keyword(s):  
North Atlantic ◽  
Fossil Record ◽  
East Coast ◽  
Late Oligocene ◽  
Deep Time ◽  
Western Atlantic ◽  
The North ◽  
Fossil Material ◽  
Phocid Seals ◽  
Critical Revision

Historically, Monotherium had been one of the few genera of extinct Phocidae (true seals) that served as a wastebin taxon. Consequently, it did neither aid in understanding phylogenetic relationships of extinct Phocidae, nor in understanding seal diversity in deep time. This urged the reassessment of the genus. Before our review, Monotherium included five different species: Monotherium aberratum , Monotherium affine , and Monotherium delognii from Belgium; Monotherium gaudini from Italy; and Monotherium ? wymani from the east coast USA. In this work we redescribe the fossil record of the genus, retaining the type species M. delognii . Monotherium aberratum and M. affine are reassigned to the new phocine genus Frisiphoca . Monotherium gaudini is renamed and considered a stem-monachine ( Noriphoca gaudini ). The holotype of the monachine M. ? wymani requires further study pending the discovery of new fossil material that could be attributed to the same taxon. Reinvestigating the stratigraphic context reveals that N. gaudini most likely represents one of the two oldest named phocid seals, or even the oldest, dated to the late Oligocene–earliest Miocene. Our results allow questioning the widespread idea that Phocidae originated in the western Atlantic and better appreciate their palaeobiogeography during the late Oligocene–Miocene interval in the North Atlantic realm.

The genus Swiftopecten Hertlein, 1936, (Bivalvia: Pectinidae) in the Tertiary of southern South America

1995 ◽  
Vol 69 (6) ◽  
pp. 1054-1059 ◽  
Author(s):  
Claudia J. Del Río
Keyword(s):  
New Species ◽  
South America ◽  
Fossil Record ◽  
Late Eocene ◽  
South American ◽  
Sedimentary Sequence ◽  
American Continent ◽  
Antarctic Region ◽  
Southern South America ◽  
South American Continent

The presence of Swiftopecten Hertlein, 1936, in Patagonia (Argentina), a region situated in the southeastern extreme of the South American continent, is the oldest and southernmost fossil record of the genus. Furthermore, its occurrence during the Late Eocene in the circum-Antarctic region suggests that its origin was in the Southern Hemisphere; it has been known from Japan and the eastern Pacific, ranging from Miocene to Holocene (Moore, 1984). Swiftopecten iheringii new species, from the Late Eocene-Early Miocene sedimentary sequence of Patagonia, is described and illustrated.

Diversification of the North American Doellingeria-Eucephalus Clade (Astereae: Asteraceae) Inferred from Molecular and Morphological Evidence

2019 ◽  
Vol 44 (4) ◽  
pp. 930-942
Author(s):  
Geraldine A. Allen ◽  
Luc Brouillet ◽  
John C. Semple ◽  
Heidi J. Guest ◽  
Robert Underhill
Keyword(s):  
North American ◽  
Sequence Data ◽  
Phylogenetic Analyses ◽  
Sister Group ◽  
Morphological Evidence ◽  
South American ◽  
New Combinations ◽  
The North ◽  
Hybridization Event ◽  
Ancient Hybridization

Abstract—Doellingeria and Eucephalus form the earliest-diverging clade of the North American Astereae lineage. Phylogenetic analyses of both nuclear and plastid sequence data show that the Doellingeria-Eucephalus clade consists of two main subclades that differ from current circumscriptions of the two genera. Doellingeria is the sister group to E. elegans, and the Doellingeria + E. elegans subclade in turn is sister to the subclade containing all remaining species of Eucephalus. In the plastid phylogeny, the two subclades are deeply divergent, a pattern that is consistent with an ancient hybridization event involving ancestral species of the Doellingeria-Eucephalus clade and an ancestral taxon of a related North American or South American group. Divergence of the two Doellingeria-Eucephalus subclades may have occurred in association with northward migration from South American ancestors. We combine these two genera under the older of the two names, Doellingeria, and propose 12 new combinations (10 species and two varieties) for all species of Eucephalus.

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