Fossilized bones of dinosaurs are like breadcrumbs to a fossil hunter. They tell us so much about the modern ecosystem and, when put in context, the evolution of dinosaurs. They can provide information on the impact of climate change on dinosaur extinction. They have contributed to the theory that humans co-existed with non-avian dinosaurs.
Did you know that scientists found fungal infection in fossilized bones of sauropod dinosaurs? Sauropods were a group of large herbivorous diapsid dinosaurs that lived during most of the Mesozoic era. A few types of fungi are commonly found in both living and dead bones. Studies done by scientists associate these fungi with bone softening, bone malformation, and bone loss in living organisms.
Scientists’ studies found a few types of fungi, namely Penicillium sp., Exophiala dermatitidis, Nigrospora sphaerica, etc., from fossilized bones of sauropods. There’s more to discover about fungal activity in fossilized bones. The following sections are just a peek into the findings on fungal activity in fossilized bones of dinosaurs.
Image courtesy of Kenneth Carpenter
What is Taphonomy?
Taphonomic is the study of how organisms decay, fossilize, and how, where, and when fossilized bone or other organic material is naturally preserved.
Trace Fossils
Trace fossils are the fossilized remains of activities of organisms. They include footprints, burrows, nests, and coprolites (fossilized feces). Scientists only recognized them in the late 1600s. Fungi, protists, and bacteria are responsible for many trace-fossil types. Bone is the most common substrate that is negatively affected by these organisms.
Fungi can alter bone in a variety of ways. Scientists can use these changes to study the biology of extinct animals and the environment they live in. Fungi are hardy organisms and have been around for a long time – at least 450 million years ago.
A new study suggests that fungi colonized fossils after they were already buried, rather than deep underground during the formation of sedimentary rock layers during mountain-building. Fungal activity can tell us a lot about what happened to bones millions of years ago.
Body Fossils
Body fossils are the remains of once-living organisms, for example, teeth, bones, shells, wood, leaves, pollen, etc. Fossils are usually formed from the remains of dead organisms. These are usually eroded by water, wind, and chemical attack. Fungi often attack fossil bones.
Fungal spores get stuck in the sticky sap and are mostly buried in the wood. Microscopic analysis of the fossilized wood revealed the presence of microfossils. It includes fungal hyphae and spores. Fungi produce spores as they have a tough outer wall called a spore coat made from chitin.
Besides skeletons, fossilized dinosaur bones are also found, although these are much less common. As a result, we have no direct evidence that dinosaurs suffered from fungal infections during their lives. One way of telling if fungi infected fossilized bones during life is to look at their internal structure.
Bones contain many blood vessels that nature can preserve as pores between their cells. (Haversian canals) after becoming fossilized. The fungi’s infection of the bone tissue causes it to die. It leads to the infilling of these spaces with minerals that seep into the bone from the surrounding rock matrix or soil. Fossilized dinosaur bones provide some cool information about ancient life forms.
The Process of Taphonomy
Scientists found fungi in fossils preserved through taphonomic processes. The most common form of preservation is mineralization. It means that minerals have replaced organic matter. Fungal activity can also lead to the preservation of organisms, but only under certain conditions.
The first stage of fungal activity is colonization, when a fungus attaches itself to an organism and begins growing on it. This process can happen during decomposition or fossilization, depending on the location of the fungus or within an organism. Once colonization has occurred, there are two main ways that fungi can help preserve an organism:
If a fungus grows directly into an organism’s body mass, it may displace other microbes and prevent them from consuming more than their share of nutrients from within the host’s body. This process will leave more nutrients for other organisms such as bacteria and archaea.
It will allow more complex life forms (such as plants) to grow and reproduce within this ecosystem. If this does not happen, there may be fewer nutrients available for other organisms within this ecosystem. It will cause them to die off over time due to starvation.
The Life Cycle of Fungus in Fossilized Dinosaur Bones
Fungal activity in fossils is not a new phenomenon. Scientists have been studying it for years. The process of fungal activity in fossilized dinosaur bones is well-documented.
In short, we know that fungi can colonize dead organic matter, including bones and teeth. They do this by a process called “saprophytism.” It happens when soil or rock has buried the organic matter.
Any fossilized dinosaur bones should have fungal activity since they have lain buried for millions of years. There are more or less ten different types of funguses found in dinosaur fossils.
1. Chytridiomycota
The live cycle of chytridiomycota fungi in dinosaur bones is a complicated process. The fungi had to survive in many different environments and conditions to infect dinosaurs buried on the Earth for millions of years.
The chytridiomycota fungi must adapt to their environment and evolve for this to happen. They have developed an incredible ability to reproduce quickly and efficiently. It means they can infect any animal.
Once they have infected an animal’s body, they will begin breaking down its cells until there is nothing left but a skeleton of chytridiomycota spores. These spores will then spread across the globe until they find another host on which they can continue their life cycle (or die out).
2. Blastocladiomycota
The bone of a dinosaur is the perfect place to live. It’s dry, it’s warm, and it’s protected from predators. Blastocladiomycota is a fungus that likes to live in the bones of dinosaurs. It has been around since dinosaurs existed, so we know it was around when they did, too.
How does this fungus get inside the dinosaur bones? When a dinosaur dies, its body starts to decay. The decomposition process involves three main stages:
- Putrefaction (the breakdown of soft tissues)
- Liquefaction (the breakdown of the bone matrix)
- Maceration (the breakdown of bone)
Oxygen enters the body of the dinosaur during these stages. It creates an environment favorable for Blastocladiomycota growth. As the decomposing body dries out over time, this environment becomes ideal for Blastocladiomycota growth. Less water is available for other organisms present at this stage in the decomposition process.
3. Zygomycetes
The little, ecologically heterogeneous, paraphyletic, or polyphyletic group is mostly terrestrial fungi. It has sporocarps called “zygosporangia.” In some species, the sporocarps form a slimy mass known as “sclerotium.” Scientists need a microscope to view the zygomycete fungus.
The zygomycete fungus enters the bones of dinosaurs through their teeth, which are porous and allow easy penetration by microorganisms. The fungus grows in their bones and gradually replaces them with its substance. The process takes several thousand years, but after that, all.
Image courtesy of Mike Guether
4. Glomeromycota
Scientists have found that fossilized bones of dinosaurs contain the remains of Glomeromycota fungus. They have also obtained the genome sequence for the fungus from a fossilized dinosaur bone discovered in the Gobi Desert in Mongolia. Researchers compared it to modern-day species to determine how the fungus could survive in this environment.
The results showed that these types of fungi are all eukaryotic and multicellular. It means they must have evolved at least 300 million years ago. It would make it possible for them to colonize land around 250 million years ago when it first appeared on Earth.
The fossils were also examined using an electron microscope. It revealed that there were structures called arbuscules present inside each cell of the structure, known as hyphae (spores). These hyphae form a symbiotic relationship with other organisms. For example, plants and animals because they provide much-needed nutrients such as carbon dioxide and nitrogenous compounds through their root systems.
5. Ascomycota
Researchers have found that fungi have been present in fossilized bones in the past decade. These fungi remain dormant until they are gradually exposed to temperature changes, and then they reactivate and begin to grow again.
The first step is for a fungus to attach itself to a bone surface through endophytes or epiphyllous fungi. Ascomycota fungi then colonize the bone surface and produce asci, which contain ascospores. These spores can germinate into hyphae and form new mycelium on the bone surface.
Mycelial growth is essential for this process because it allows the fungus to compete with other organisms for nutrients and space within its niche. Once established, ascomycetes produce more spores. They can germinate into hyphae and form new colonies of ascomycetes on other bones. They can also do it in the soil nearby, where they live with other organisms such as bacteria or algae (Fossilised Bones).
6. Basidiomycota
As dinosaurs roamed the Earth, their bones were home to various fungi. One group, in particular, Basidiomycota, is commonly known for its ability to live in the most unlikely places. The fossilized bones of dinosaurs are no exception. It’s estimated that more than half of all dinosaur fossils have some fungal activity on them.
Basidiomycota is one of the three main groups of mushrooms. They are also called club fungi because their spores develop in basidia (hence “basidiomycetes”). You can see these spores with the naked eye on the edges of fruiting bodies called basidiocarps or mushrooms.
Scientists call the most common type of Basidiomycota found on dinosaur fossils Phallus indusiate. It is a pale yellow-orange color and grows about 1 cm wide by 3 cm long. It produces spores at the end of a tube called an ascus (hence “Phallus” indusiate). These tiny spore-producing structures make up this fungal species’ habitat: fossilized dinosaur bone. 
7. Lichen
The Lichen fungi are ancient symbiotic organisms that have adapted over time to live in three-dimensional hyphal net enclosing unicells. The green algae and cyanobacteria provide sugar alcohols and glucose to the fungus. It protects them from extreme weather conditions and predators. The Lichen fungi also absorb moisture from rain and snow, which helps keep their environment moist.
The green algae and cyanobacteria need to be morphologically similar to their partner to maintain this partnership. For example, if one partner has a red color, the other must be yellow. This way, they can coordinate with each other for optimal growth.
The partnership between these organisms dates back to the Precambrian era when there was only one Earth mass called Pangaea. When it broke apart into several continents, it caused climate change. It leads to increased chemical weathering of crustose lichens on rocks.
8. Penicillium spp
The fossilized bone of dinosaurs contains a fungal activity. The fungus is Penicillium spp, an important decomposing agent that breaks down dead plants and animals.
Penicillium spp can grow in various environments, such as soil, leaves, rotting fruits, and even on walls. They are also known as bread molds because they grow on bread and other plant-based foods if left out in the open air.
The fossilized bones of dinosaurs contain Penicillium spp, which indicates that they were once exposed to oxygen. It was before being deeply buried beneath the Earth during their lifetime. These dinosaurs were likely buried in soil during their lives or immediately after death. Otherwise, the oxygen would not have been present for Penicillium sp. to grow within them.
9. Exophiala Dermatitidis
The Exophiala dermatitidis fungus is a fungus that lives on dead animals and has been regularly found in fossilized bones. This fungus can damage the bones, causing them to crumble.
Parent fungus produces spores and spreads them through the air. The spores land on the surface of a host organism and start to grow inside them. It can happen when a dinosaur dies, and its body falls apart, exposing its bones to fungal spores. It could also happen if an existing fungal infection is already on an animal’s skin and gets into an open wound while alive (for example, if they get scratched).
Once inside their host organism, these spores will grow into hyphae (the microscopic root-like structures that make up fungi). These hyphae produce more spores that then disperse throughout their body again. These spores will come back onto their skin so they can be continually spread around by wind currents instead.
10. Nigrospora Sphaerica
Nigrospora sphaerica is a soil-borne fungus that attacks animal bones, especially those of reptiles and mammals. The fossil record shows that this fungus has existed since at least the Jurassic period (250 million years ago). It infects the bone by colonizing the surface and then penetrating the inside. Once inside, it grows in a network of fine hyphae (the filaments that make up fungal tissue).
The hyphae absorb nutrients from the bone, which they metabolize into organic acids that dissolve calcium phosphate crystals within the bone matrix. These organic acids also make it easier for them to grow by increasing their water content. It causes more damage to the bone matrix as it dissolves more crystals and provides more nutrients for them.
As the bone matrix becomes damaged, it becomes less structured and harder for new cells to grow there. Its ability to regenerate decreases over time and its strength and thickness. Its mechanical properties become like soft tissue rather than hard tissue such as bone or tooth enamel.
Fungal Spores
Fossil fungal spores, hyphae, etc., are a common component of most palynological preparations. Microfossils are tiny, dispersed remains of organisms. They are commonly found preserved in sediments and unconsolidated sediments.
The fossilized hyphae can help determine the paleoecosystem. In other words, the origins of the conditions that created them and what kind of dinosaurs they came from.
Scientists can determine Paleoecosystem conditions by looking at the distribution and abundance of fossilized hyphae. Researchers can then use data on their abundance and distribution to gain insight. For example, how many spores were present at one time and what their whereabouts were while they were alive.
This data helps us understand what kind of environment existed during the dinosaur era when dinosaurs roamed around Earth before going extinct due to meteorite impact at the end-Cretaceous period 65 million years ago.
Dispersed microfossils are collectively referred to as non-pollen palynomorphs or NPPs. It includes cyanobacteria, algae, and aquatic invertebrates). They have been widely applied to paleogeography in stratigraphy, paleoecology, and depositional environment analysis.
Final Thoughts
Fungal spores may remain intact in bone fossils. We can learn the life cycles of dinosaurs and other extinct animals by using fungal spores found in dinosaur bone fossils. It is a valuable tool for paleontologists and has helped them better understand the biology and diversity of dinosaurs through time.
As you may have realized by now, fungi are useful for breaking down dead organic matter. They are often essential for recycling nutrients back into the soil used to nourish new life. Whether a dinosaur was alive and well at the time of death or was already long dead and in a state of advanced decay, fungi would have been present to break down its remains.
We can only speculate about their presence in such far-distant times. These little organisms have certainly been around since dinosaurs were roaming the Earth billions of years ago and will likely be around for many centuries.
