Three species of trepostome bryozoans formed syn vivo associations with the Cornulites in the Late Ordovician of Estonia. Cornulites sp. and Mesotrypa excentrica presumably formed a true symbiotic association. This is the first known case of symbiosis between cornulitids and bryozoans. It is not known whether this symbiotic association was obligatory of facultative for the cornulitid, but it was facultative for the bryozoan. In this association cornulitids may have competed for the food with bryozoans and the association may have been parasitic. The remaining associations between cornulitids and bryozoans were accidental. Most common skeletonized endobionts of the Ordovician bryozoans were not cornulitids, but conulariids and rugosans.

The Upper Pennsylvanian (Virgilian) Halgaito Formation (HF) is an ∼ 125–155-m-thick succession of carbonate and carbonate-cemented siliciclastic strata exposed along Cedar Mesa on the Colorado Plateau in southeastern Utah. Defining the stratigraphic standing of the HF has been problematic due to differing paleoenvironmental and paleogeographic interpretations. This stratigraphic confusion is likely because the HF and overlying Cedar Mesa Sandstone lie at the interface between the underlying, predominately marine carbonate Honaker Trail Formation and the overlying, alluvial-eolian Organ Rock Formation. This study uses a combined ichnological, paleopedological, and sedimentological approach to refine the paleoenvironmental and paleogeographic history of the HF. The lower, marine portion of the HF is predominately fossiliferous packstone and calcareous sandstone, containing abundant Scalichnus and Thalassinoides. Marine sandstone beds contain shallow rhizoliths and indicate a relative sea-level drop that was punctuated by at least four, small-scale transgressions. The upper, continental section contains predominately eolian siltstone with siliciclastic Entisols and mottled Inceptisols. These paleosols contain large rhizohaloes and calcareous rhizocretions that are commonly associated with abundant Naktodemasis bowni. The uppermost ∼ 40 m of strata are laminated and crossbedded siltstone that contain little to no paleopedogenic development and few ichnofossils. These eolian beds were likely sourced from the erosion of underlying marine strata of the Hermosa Group as the Elephant Canyon Seaway regressed northward during the Pennsylvanian. Thin, coarse-grained fluvial strata can be observed throughout the HF and were likely sourced from the highlands of the Uncompahgre Uplift.

Lepidenteron mantelli is a trace fossil produced by a burrowing marine invertebrate (probably a polychaete) that sequestered plant macroremains in Cenomanian–Coniacian marly calcareous sediments of the Central European Basin during transgression events. For more than a century and half, this trace fossil has been mistaken for a fossil plant. In this paper, L. mantelli is described from upper Turonian marly limestones deposited under offshore, oligotrophic conditions in the Opole Trough, Southern Poland and its taxonomy and occurrences are summarized. Based on detailed studies of pyrite microtexture on wood fragments within the burrow and surrounding sediment, the feeding strategy of the L. mantelli trace maker is interpreted.

The present study is a holistic approach to the relationship between volcaniclastic host rock characteristics and the fossilization processes of short leafy coniferous branches of Squamastrobus tigrensis, preserved as fossilized-cuticles (Lower Cretaceous, Baqueró Group, Patagonia, Argentina). The question of diagenetic influences of Aptian volcaniclastic sedimentation on preservation chemistry and taphonomic processes is addressed. Whereas infrared spectroscopy provided chemical information on the leaves, vitrinite reflectance and complementary thermal indicators provided data on the thermal maturity of the dispersed organic matter in the host rock. Three sample types were analyzed: fossilized-cuticle, macerated fossilized-cuticle (by infrared spectroscopy), and associated organic host rock matter (by light microscopy). Results clearly show chemical variability between, and within the fossilized-cuticle and cuticle, as well as a similarity to type I/II kerogen, i.e., high contents of both aliphatic groups and oxygen-containing compounds. Combined with the lower maturity of the host rock, the importance of the depositional environment during burial and taphonomic conditions that affected the fossilization of S. tigrensis are summarized in a general fossilization model.

The study of plant-insect interactions provides valuable information about the ecology of feeding behavior and the relationships between the host plant and the producer insect. Records of feeding traces are relatively rare for the Miocene of South America. Here, new records of plant-insect interactions on dicot leaves and fern fronds from the middle and late Miocene of Argentina are presented. In total, 1204 dicot and fern impressions were analyzed including 384 from the San José Formation and 856 from the Palo Pintado Formation. Traces of arthropod herbivory are found on 303 foliar impressions, 288 from the Palo Pintado Formation and just 15 from the San José Formation. Forty-four percent of all traces were found on Thelypteris interrupta (Willd.) Iwatsuki 1963 (Thelypteridaceae), followed by Cedrela fissiliformis Anzótegui and Horn 2011 (Meliaceae) (15.1%) and Schinus herbstii Anzótegui 1998 (Anacardiaceae) (11.3%). Thelypteris interrupta is associated with a low diversity of Damage Types, mainly hole and window feedings, indicating a monospecific relationship with the trace maker. On the other hand, the high abundance and diversity of damage types found on C. fissiliformis and S. herbstii denote that these plants were hosting a more diverse group of arthropods. Likewise, the lower number of traces identified in the San José Formation corresponds to the xeric conditions established during the middle Miocene in northwestern Argentina. These conditions changed in the late Miocene, at least in some regions, to a humid climate, promoting an increase in phytophagy that is evidenced by the abundance recorded in the Palo Pintado Formation.