92
insects (Fig. 3.4l) (Sung et al. 2008). This fossil provides the oldest compelling
evidence of animal parasitism by fungi, and is characterized by several synnemata
emerging from the head of the host. However, there is no evidence indicative of host
behavior manipulation. The third example is a trace fossil that occurs in the form of
well-preserved death-grip scars in Eocene (48 Ma) angiosperm leaves from the
Messel pit in Germany (Hughes et al. 2011b). The characteristic scars are remarkably similar to the death-grip scars produced by some present-day fungus-infected
carpenter ants (Hughes et al. 2011a).
3.3.4.4 Dinosaurs
Some of the first animals that come to mind when we think of life in the geologic
past are dinosaurs. There are limited reports of pathogenic fungi associated with
dinosaur remains. One possible example is a Tyrannosaurus rex mandible that
shows multiple erosive lesions (Rega and Brochu 2001; Wolff et al. 2009; but see
Rothschild and Martin 2006; Watson and Rothschild 2021 for alternative interpretations). The authors postulate that such abscesses may eventually form large, localized caseous masses which would be susceptible to fungal parasitic infections,
similar to those seen in modern crocodilians (Huchzermeyer 2003). Another interesting example includes fossilized Cretaceous sauropod dung from India that contains an array of fungal remains, including forms that are known to be plant parasites
(e.g., Colletotrichum), thus indicating that some sauropods ate the leaves of fungusinfected plants as food (Kar et al. 2004). Other sauropod coprolites from India contain several different fungal remains characteristic of present-day plant pathogens,
including Colletotrichum- like acervuli (leaf spot, red rot disease), Erysiphe- and
Uncinula-like cleistothecia (powdery mildew), and black spot-producing microthyriaceous ascostromata (Sharma et al. 2005). A single specimen of an infected
grass spikelet with similarities to extant Claviceps purpurea (commonly known as
ergot) has been identified in Cretaceous Myanmar amber (Poinar 2015). The authors
suggest that, if ergot- infected grass was ingested by herbivore animals, they may
have felt the effects of the psychotropic compounds produced by the fungus in a
similar way to that seen in livestock animals today (Bove 1970). Finally, numerous
large coprolites from three different horizons (spanning at least 6 Ma) within the
Upper Cretaceous Two Medicine Formation of Montana have revealed that some
herbivorous dinosaurs sometimes consumed large amounts of fungus-infected wood
(Chin 2007). This author states that decaying wood would have provided an assortment of nutritious foods, including cellulose from the wood, fungi, other microbes,
and detritivorous invertebrates.
Some investigators even have suggested that fungal parasites may have contributed to the demise of the dinosaurs at the end of the Cretaceous. Several dinosaur
eggs have been reported with mycelium-like structures or endolithic fungi in the
eggshells (Gong et al. 2008). Based on fungal morphology and the areas in the
shells in which the fungi occur, it has been hypothesized that the fungi were parasitic and invaded the eggs before they became lithified. A very provocative hypothesis regarding the extinction of dinosaurs relating to fungal infections by Casadevall
C. J. Harper and M. Krings
insects (Fig. 3.4l) (Sung et al. 2008). This fossil provides the oldest compelling
evidence of animal parasitism by fungi, and is characterized by several synnemata
emerging from the head of the host. However, there is no evidence indicative of host
behavior manipulation. The third example is a trace fossil that occurs in the form of
well-preserved death-grip scars in Eocene (48 Ma) angiosperm leaves from the
Messel pit in Germany (Hughes et al. 2011b). The characteristic scars are remarkably similar to the death-grip scars produced by some present-day fungus-infected
carpenter ants (Hughes et al. 2011a).
3.3.4.4 Dinosaurs
Some of the first animals that come to mind when we think of life in the geologic
past are dinosaurs. There are limited reports of pathogenic fungi associated with
dinosaur remains. One possible example is a Tyrannosaurus rex mandible that
shows multiple erosive lesions (Rega and Brochu 2001; Wolff et al. 2009; but see
Rothschild and Martin 2006; Watson and Rothschild 2021 for alternative interpretations). The authors postulate that such abscesses may eventually form large, localized caseous masses which would be susceptible to fungal parasitic infections,
similar to those seen in modern crocodilians (Huchzermeyer 2003). Another interesting example includes fossilized Cretaceous sauropod dung from India that contains an array of fungal remains, including forms that are known to be plant parasites
(e.g., Colletotrichum), thus indicating that some sauropods ate the leaves of fungusinfected plants as food (Kar et al. 2004). Other sauropod coprolites from India contain several different fungal remains characteristic of present-day plant pathogens,
including Colletotrichum- like acervuli (leaf spot, red rot disease), Erysiphe- and
Uncinula-like cleistothecia (powdery mildew), and black spot-producing microthyriaceous ascostromata (Sharma et al. 2005). A single specimen of an infected
grass spikelet with similarities to extant Claviceps purpurea (commonly known as
ergot) has been identified in Cretaceous Myanmar amber (Poinar 2015). The authors
suggest that, if ergot- infected grass was ingested by herbivore animals, they may
have felt the effects of the psychotropic compounds produced by the fungus in a
similar way to that seen in livestock animals today (Bove 1970). Finally, numerous
large coprolites from three different horizons (spanning at least 6 Ma) within the
Upper Cretaceous Two Medicine Formation of Montana have revealed that some
herbivorous dinosaurs sometimes consumed large amounts of fungus-infected wood
(Chin 2007). This author states that decaying wood would have provided an assortment of nutritious foods, including cellulose from the wood, fungi, other microbes,
and detritivorous invertebrates.
Some investigators even have suggested that fungal parasites may have contributed to the demise of the dinosaurs at the end of the Cretaceous. Several dinosaur
eggs have been reported with mycelium-like structures or endolithic fungi in the
eggshells (Gong et al. 2008). Based on fungal morphology and the areas in the
shells in which the fungi occur, it has been hypothesized that the fungi were parasitic and invaded the eggs before they became lithified. A very provocative hypothesis regarding the extinction of dinosaurs relating to fungal infections by Casadevall
C. J. Harper and M. Krings