Department of Paleobiologyhttps://hdl.handle.net/10088/28452024-03-29T02:22:27Z2024-03-29T02:22:27ZPaleoecological Significance of Trace Fossils and Fossil Plants from a New Locality in the Upper Part of the Abo Formation (Lower Permian), Socorro County, New MexicoLucas, Spencer G.DiMichele, William A.Harris, Susan K.May, Paul T.Kerp, Hanshttps://hdl.handle.net/10088/1175392024-03-05T02:40:10Z2023-01-01T00:00:00ZPaleoecological Significance of Trace Fossils and Fossil Plants from a New Locality in the Upper Part of the Abo Formation (Lower Permian), Socorro County, New Mexico
Lucas, Spencer G.; DiMichele, William A.; Harris, Susan K.; May, Paul T.; Kerp, Hans
A recently discovered tracksite in the Abo Formation in the Quebradas region of Socorro County is distinguished by unusually high ichnodiversity and exceptional preservation. This site, NMMNH (New Mexico Museum of Natural History) locality 12617, is north of Tinajas Arroyo in the Cañon de Espinoso Member of the Abo Formation, about 5 meters below the base of the overlying Yeso Group. The fossil-bearing stratum is a 0.7-1.5 m thick interval of thin-bedded, ripple-laminated, very fine sandstone with extensive mudcracks. At locality 12617, many surfaces with trace fossils have microbially induced sedimentary structures (MISS), and microbial mediation of preservation likely caused some of the exceptional ichnofossil preservation at this site. The invertebrate trace (ribbon trail) Olivellites (= Psammichnites) is reported here from the Abo Formation for the first time. Tetrapod ichnogenera from locality 12617 are Amphisauropus, Batrachichnus, Dromopus, Dimetropus, Limnopus and Varanopus. Plant specimens consist of the conifer Walchia, the peltasperm Supaia, and the callipterid Autunia conferta. Walchia and Supaia are typical of the Abo Formation throughout its extent; most Abo fossil plant sites are dominated by conifer remains of several types, but some fewer by Supaia. Mixed assemblages are uncommon. Autunia conferta, of the small-pinnule type, is common only in the upper Abo Formation (Cañon de Espinoso Member). The ichnofaunal composition at NMMNH locality 12617, which is dominated by anamniote, parareptile/eureptile and synapsid tracks, is very different from that of the Erpetopus biochron just above it. This is consistent with data from North America and Europe that identify a substantial change in the composition of footprint ichnoassemblages at the beginning of the Erpetopus biochron (close to the beginning of the Leonardian) due to the diversification of sauropsid reptiles, likely driven by climate changes (drying) across much of Pangea. Indeed, paleoenvironmental changes across the Abo-Yeso transition—regional marine transgression and a trend towards drier climates—are well reflected in the changes in trace fossil and floral composition during the early Leonardian.
2023-01-01T00:00:00ZTwo Early Permian Fossil Floras from the Arroyo De Alamillo Formation of the Yeso Group, Socorro County, New MexicoDiMichele, William A.Lucas, Spencer G.Kerp, HansMay, Paul T.https://hdl.handle.net/10088/1175332024-03-05T02:39:58Z2023-01-01T00:00:00ZTwo Early Permian Fossil Floras from the Arroyo De Alamillo Formation of the Yeso Group, Socorro County, New Mexico
DiMichele, William A.; Lucas, Spencer G.; Kerp, Hans; May, Paul T.
We report fossil plants and traces from the Arroyo de Alamillo Formation of the Yeso Group, a lithologic succession of siltstone, sandstone, and minor dolostone and gypsum of early Permian (early Leonardian/late Artinskian) age. These Yeso strata formed under a semi-arid to arid climate regime on a vast coastal plain, conditions generally unfavorable for the preservation of fossil remains. Two fossil plant assemblages were collected from a single outcrop in Socorro County, New Mexico, ~9 and ~13 m above the base of the Arroyo de Alamillo Formation. The lower of the two assemblages occurs in a mud-draped, tabular siltstone bed, approximately 1 m in thickness; the mud drape accounts for the upper 1 cm of the bed. This bed is similar to much of the underlying Abo Formation and is interpreted to have formed in a playa lake. Plant remains are concentrated in the mud drapes and occur with animal trackways, mudcracks, and “raindrop” imprints. Identified plants include the walchian conifer, Brachyphyllum tenue, and remains tentatively identified as a coniferophyte similar to Dicranophyllum, but lacking key features of that genus. The upper plant assemblage is ~ 4 m above the first. Plant remains are present in a 0.5 m thick, fine-grained sandstone bed. Planar bedded and lacking trough cross bedding, with climbing ripples, we interpret this deposit as a small-scale sheet flood, unchannelized flow, into a standing water pond, possibly an oasis in an otherwise arid, sand-rich landscape. The fossil plants occur in a small area approximately 2 m in width and 30 cm in depth, length limited by the erosional boundaries of the outcrop to about 3 m. With the exception of a few specimens, all plant remains can be assigned to the peltasperm (callipterid) Autunia naumanii. Single specimens are tentatively identified as the peltasperm Arnhardtia scheibei and reproductive organs. These are among the youngest occurrences of plant fossils so far reported in the early Permian of western Pangea.
2023-01-01T00:00:00ZRemington Kellogg 1892-1969Whitmore, Frank C.https://hdl.handle.net/10088/1172042023-09-21T01:31:06Z1983-01-01T00:00:00ZRemington Kellogg 1892-1969
Whitmore, Frank C.
1983-01-01T00:00:00ZPollen Analysis of the Peat Member from the Lee Creek MineWhitehead, Donald R.https://hdl.handle.net/10088/1172032023-09-21T01:31:06Z1983-01-01T00:00:00ZPollen Analysis of the Peat Member from the Lee Creek Mine
Whitehead, Donald R.
1983-01-01T00:00:00Z