The Lauers are back with more science! The paper “Microcoprolite morphotypes from the Revueltian (Upper Triassic: Norian) age Homestead Site, Garita Creek Formation, east-central New Mexico, USA” was published in the journal Ichnos, which is an international journal for plant and animal traces.

This one is about various microcoprolite morphotypes from the Homestead Site in the Garita Creek Formation in east central New Mexico, which is known for its rich fossil assemblage of archosaurs, lepidosaurs, fish, and temnospondyls. Coprolites are extremely abundant at the site. The authors studied 600 coprolites to better understand the animals living in that environment and how they interacted. They found ~53% of the coprolites had fossil inclusions and 70% of those had inclusions on the surface, which made it cheaper (no CT scanning or synchrotron imaging needed) and easier to determine the fossil contents.

The authors concluded that the coprolites indicate the Homestead Site was a complex aquatic ecosystem, maybe a floodplain or oxbow lake, which was the home of sharks, lungfish, coelacanths, ray-finned fishes, temnospondyls, and reptiles like archosaurs and lepidosaurs. This paper highlights that even tiny coprolites can preserve detailed evidence of predator-prey relationships, digestive anatomy, and ecosystem structure in Late Triassic environments.

Microcoprolite morphotypes from the Revueltian (Upper Triassic:
Norian) age Homestead Site, Garita Creek Formation, east-central
New Mexico, USA

Abstract
The Homestead Site at Garita Creek is an Upper Triassic locality within the Garita Creek Formation of east-central New Mexico of Revueltian (Norian) age. In addition to abundant bones, scales, and teeth, thousands of coprolites make up a significant portion of the rich collection. Like the bones themselves, coprolites provide insight into the disparity of the assemblage, as coprolite morphologies are important indicators of paleoecological relationships. We examined a subset of 600 microcoprolites from the Homestead Site, finding that 316 (53%) preserve fossil inclusions, often ganoid scales, in either external (73%) or cross-sectional (27%) view, 22 (4%) bear abiotic inclusions, and 262 (44%) bear no visible inclusions. Most inclusions are visible externally, indicating that most coprolites do not require ‘digital dissection’ to determine whether inclusions are present. We identify four coprolite morphotypes: striated, cylindrical, spiral, and scroll, and those deemed nondiagnostic (too fragmentary and/or featureless). Of the 316 fossil-bearing coprolites, 22 (7%) are striated, 133 (42%) are cylindrical, 139 (44%) are spiral, 2 (1%) are scroll, and 20 (6%) are nondiagnostic. There is a well-defined ichnotaxonomy associated with Triassic coprolites. Striated coprolites align with the concept of Alococopros, and are interpreted to represent diapsid or temnospondyl perpetrators. Spiral coprolites align with the concept of Heteropolacopros and Saurocopros, and scroll coprolites align with the concept of Tikicopros, all of which are thought to represent spiral-valved chondrichthyan and/or sarcopterygian perpetrators. Within the context of the Homestead Site, coelacanths and lungfish are the only known taxa to have reached sufficient size to perpetrate the spiral coprolites. Cylindrical coprolites align with the concept of Eucoprus and within the context of the Homestead Site were likely perpetrated by actinopterygians. Our survey supports the hypothesis of the Homestead Site representing a diverse assemblage of fish and tetrapods interacting in a complex aquatic ecosystem.

Highlights

• Four coprolite morphotypes have been identified from the Homestead Site at Garita Creek: Striated, Spiral, Scroll, and Cylindrical.
• Inclusions are frequently visible on the exterior of coprolites.
• The Homestead Site at Garita Creek microcoprolite assemblage corroborates a rich skeletal record of archosaurs, lepidosaurs, fish, and temnospondyls.
• The coprolite assemblage at the Homestead Site of Garita Creek supports the notion of the site being an aquatic ecosystem.
• Most coprolites do not appear to need digital dissection methods to see signs of inclusions.