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| Borealopelta markmitchelli Brown, et al., 2017
in Brown, Greenwood, Kalyniuk, et al., 2020.
Illustration by Julius Csotonyi.
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Abstract
The exceptionally well-preserved holotype of the armoured dinosaur Borealopelta markmitchelli (Ornithischia; Nodosauridae) from the Early Cretaceous (Clearwater Formation) of northern Alberta preserves a distinct mass within the abdominal cavity. Fourteen independent criteria (including: co-allochthony, anatomical position, gastroliths) support the interpretation of this mass as ingested stomach contents—a cololite. Palynomorphs in the cololite are a subset of the more diverse external sample. Analysis of the cololite documents well-preserved plant material dominated by leaf tissue (88%), including intact sporangia, leaf cross-sections and cuticle, but also including stems, wood and charcoal. The leaf fraction is dominated (85%) by leptosporangiate ferns (subclass Polypodiidae), with low cycad–cycadophyte (3%) and trace conifer foliage. These data represent the most well-supported and detailed direct evidence of diet in an herbivorous dinosaur. Details of the dietary palaeoecology of this nodosaur are revealed, including: selective feeding on ferns; preferential ingestion of leptosporangiate ferns to the exclusion of Osmundaceae and eusporangiate ferns such as Marattiaceae; and incidental consumption of cycad–cycadophyte and conifer leaves. The presence of significant (6%) charcoal may represent the dietary use of recently burned conifer forest undergoing fern succession, early evidence of a fire succession ecology, as is associated with many modern large herbivores.
Keywords: cololite, Ankylosauria, diet, Canada, Clearwater Formation, Cretaceous
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| Figure 1. Location of abdominal mass, including stomach contents (cololite), within the well-preserved nodosaur Borealopelta markmitchelli (TMP 2011.033.0001). Photograph (a) and scientific line drawing (b) of the specimen in dorsal view. Schematic drawing (c) of specimen showing position and extent of abdominal mass, as well as extrapolated body outline. Inset (d) of i, showing close up photograph of dorsal view of posterior margin of abdominal mass. Inset (e) of ii, showing detailed map of extent of abdominal mass. (f) Schematic drawing of Kunbarrasaurus ieversi (GM F18101) scaled to (c), showing relative size and positon of cololite. Solid orange, observed cololite; hatched orange, inferred cololite. A, anterior; L, lateral. Scale bars in (a,b,c,f) are 1 m, and in (d,e) are 10 cm. |
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| Figure 4. Palaeobotanical elements observed on the cololite histological slides. (a) Clubmoss (Lycopodiopsida) sporangium type C with Echinatisporis sp. (Lycopodiaceae or Selaginellaceae), (b–d) isolated leptosporangiate fern sporangia with spores in situ, (b) sporangium type F with Cicatricosisporites sp. (Schizaeaceae), (c) sporangium type E with Deltoidospora sp. (fam. indet.) or Biretrisporites sp. (Matoniaceae-Cyatheaceae-Dicksoniaceae), (d) sporangium type A (spore indet.), (e) charcoal/blackened plant fragment, (f) square stem cross-section, (g) cuticle without stomata displaying sinuous lateral cell walls (Type 1), (h) leaf cross section, (i) cuticle with stomata and sinuous lateral cell walls (Type 2), (j) cuticle with stomata Type B, (k) thickened cells/ sclerenchyma, (l) cuticle with stomata (Type A), (m) twig cross-section showing annual rings. (c,d,j,k) scale bars = 40 µm; (a,b,e,g,h,i,l) scale bars = 100 µm; (m,f) scale bars = 400 µm. |
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| Figure 6. Composition of the cololite determined from microscopy of thin sections. (a) Breakdown of slide area (slide 2 only) occupied by gastroliths, matrix, plant fragments and void space as only slide 2 was scored for the non-plant composition. Breakdown of the plant fragment composition only (across all slides) into tissue types (b) and leaf specific tissue types. Breakdown of plant fragments (across all slides) into broad taxonomic groups (c). |
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| Figure 3. Gates Formation (Grand Cache Member) plant fossils from central Alberta. (a) Pterophyllum sp. (TMP 1990.027.0021), (b) Sphenopteris sp. (TMP 1981.055.0103), (c) Gleichenites sp. (USask 925-7273), (d) Ginkgoites sp. (TMP 1990.027.0020), (e) Taeniopteris sp. (TMP 1981.055.0006), (f) Cladophlebis sp. (top left) and Elatides sp. (arrow) (TMP 1981.055.0012), (g) Elatides curvifolia (TMP 2015.006.0469), (h) Sagenopteris sp. (TMP 1981.055.0033), (i) Equisetites sp. (USask 750-7557), (j) conifer cone (TMP 1981.055.0044) and (k) Coniopteris sp. (TMP 1981.055.0058). Scale bars = 1 cm. |
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| Life reconstruction of the Cretaceous Period armoured dinosaur Borealopelta markmitchelli, which lived 110 million years ago in what is now Alberta, eating ferns.
Royal Tyrrell Museum of Palaeontology. Illustration by Julius Csotonyi.
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Caleb M. Brown, David R. Greenwood, Jessica E. Kalyniuk, Dennis R. Braman, Donald M. Henderson, Cathy L. Greenwood and James F. Basinger. 2020. Dietary Palaeoecology of An Early Cretaceous Armoured Dinosaur (Ornithischia; Nodosauridae) Based on Floral Analysis of Stomach Contents. Royal Society Open Science. DOI: 10.1098/rsos.200305
A Nodosaur’s Last Meal
The world’s best-preserved armoured dinosaur, the nodosaur Borealopelta markmitchelli, continues to answer important questions about its biology and behaviour.
