PALEOENVIRONMENTAL IMPLICATIONS OF INVERTEBRATE FECAL PELLETS (EDAPHICHNIUM ISP.) AT AN ICHNOFOSSIL-RICH DINOSAUR NESTING LOCALITY, UPPER CRETACEOUS TWO MEDICINE FORMATION, MONTANA, USA

IF 1.5 4区地球科学 Q2 GEOLOGY

Palaios Pub Date : 2021-09-04 DOI:10.2110/palo.2021.003

William J. Freimuth, D. Varricchio, K. Chin

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Abstract

Abstract: The terrestrial feeding trace Edaphichnium lumbricatum is known from the Triassic to the Pleistocene and is characterized by tubular burrows with ellipsoidal fecal pellets, indicating substrate feeding by earthworms or other invertebrates. We describe 11 specimens attributable to Edaphichnium isp. from Egg Mountain, a terrestrial locality with a diverse fossil assemblage from the Upper Cretaceous Two Medicine Formation in Montana, USA, and assess their paleoenvironmental and paleoecological implications. These ichnofossils were recovered from a 1.5 meter stratigraphic succession comprised of calcareous siltstones and limestones with abundant fossil insect pupal cases, representing well-drained paleosols. Although burrows are not always present, three recurring arrangements of Edaphichnium isp. fecal pellets are identified: linearly arranged pellets, horizon-confined pellets, and pellets in clusters dispersed vertically and horizontally throughout the matrix. Two color patterns (light and dark pellets) are also distinguished. Pellets are fine-grained and have a consistently ellipsoidal shape (length:diameter of 1.57), with maximum lengths ranging from 1.9–6.7 mm (mean 4.1 mm) and maximum diameters ranging from 1.0–4.1 mm (mean 2.6 mm). Geochemical analyses indicate pellets are comprised of varying proportions of calcite, plagioclase, and quartz, and are enriched in phosphorus relative to the sedimentary host matrix. Possible trace makers include chafer or other coleopteran larvae, millipedes, and earthworms, suggesting a range of capable trace makers of Edaphichnium-like fecal pellets. Edaphichnium isp. at specific stratigraphic horizons suggests increased organic content in the subsurface, potentially connected to depositional hiatuses. Edaphichnium isp. adds a secondary component to the Celliforma ichnofacies known from Egg Mountain and surrounding strata, and to the array of nesting, feeding, and dwelling traces of wasps, beetles, other invertebrates, mammals, and dinosaurs from the locality.

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美国蒙大拿州上白垩纪二药组化石化石化石丰富的恐龙筑巢地无脊椎动物粪便颗粒的古环境意义

摘要：已知的陆生食物痕迹是从三叠纪到更新世，其特征是管状洞穴和椭圆形粪便颗粒，表明蚯蚓或其他无脊椎动物以基质为食。我们描述了11个可归属于Edaphichnium isp的标本。来自蛋山，这是一个陆地地区，拥有来自美国蒙大拿州上白垩纪Two Medicine组的各种化石组合，并评估其古环境和古生态意义。这些遗迹化石是从1.5米的地层序列中发现的，该地层序列由钙质粉砂岩和石灰岩组成，并有大量昆虫蛹化石，代表排水良好的古土壤。尽管洞穴并不总是存在，但Edaphichinium的三种重复排列是有区别的。粪便颗粒被鉴定为：线性排列的颗粒、水平限制的颗粒以及垂直和水平分散在整个基质中的成簇颗粒。还区分了两种颜色模式（浅色和深色颗粒）。颗粒细粒度，具有一致的椭球形状（长度：直径1.57），最大长度范围为1.9–6.7 mm（平均4.1 mm），最大直径范围为1.0–4.1 mm（平均2.6 mm）。地球化学分析表明，颗粒由不同比例的方解石、斜长石和石英组成，并且相对于沉积宿主基质富含磷。可能的微量元素制造者包括金龟子或其他鞘翅目幼虫、千足虫和蚯蚓，这表明有一系列有能力制造类似爱德华菌的粪便颗粒。Edaphichnium isp。在特定的地层层位，表明地下有机物含量增加，可能与沉积间断有关。Edaphichnium isp。为蛋山和周围地层中已知的Celliforma遗迹相，以及当地黄蜂、甲虫、其他无脊椎动物、哺乳动物和恐龙的一系列筑巢、觅食和居住痕迹添加了次要成分。

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来源期刊

Palaios 地学-地质学

CiteScore

2.80

自引率

12.50%

发文量

审稿时长

6 months

期刊介绍： PALAIOS is a monthly journal, founded in 1986, dedicated to emphasizing the impact of life on Earth''s history as recorded in the paleontological and sedimentological records. PALAIOS disseminates information to an international spectrum of geologists and biologists interested in a broad range of topics, including, but not limited to, biogeochemistry, ichnology, paleoclimatology, paleoecology, paleoceanography, sedimentology, stratigraphy, geomicrobiology, paleobiogeochemistry, and astrobiology. PALAIOS publishes original papers that emphasize using paleontology to answer important geological and biological questions that further our understanding of Earth history. Accordingly, manuscripts whose subject matter and conclusions have broader geologic implications are much more likely to be selected for publication. Given that the purpose of PALAIOS is to generate enthusiasm for paleontology among a broad spectrum of readers, the editors request the following: titles that generate immediate interest; abstracts that emphasize important conclusions; illustrations of professional caliber used in place of words; and lively, yet scholarly, text.