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Since the mid-1800s, paleontologists have been digging up dinosaur bones. Organic molecules such as DNA and proteins are not supposed to survive in millions of years old fossils.
Scientists based the theory on the fact that organic molecules are more exposed to high temperatures and humidity after death. It can cause the molecules to break down and decompose over long periods. Scientists assume these fossils no longer provide clues to what dinosaurs looked like when they lived.
In 2005, Schweitzer and colleagues announced the discovery of soft tissue in a T-Rex fossil. The researchers found chemicals and proteins left in the fossilized dinosaur bones. Nature has preserved It for over 65 million years. After this discovery, researchers studied how organic compounds can survive for so long in fossils that previously only contained minerals.
Let’s look at what scientists found in dinosaur remains and how those findings have helped us understand more about the T-Rex and its extinct friends.
Organic Compounds
The four main classes of organic compounds detected in samples of dinosaur fossils include:
1. Pigments
The pigments in the body usually determine the color of a dinosaur. The most common pigments of living organisms are chlorophyll. It gives rise to green plants and heme, generating red blood cells for animals. Feather colors depend on the structure of keratin because of melanin and porphyrin pigments.
Heme
Heme is a red pigment molecule found within the dinosaur fossils’ soft tissue and was first used to create a chemical indicator dye for iron.
Dinosaurs evolved over 200 million years, but they died after a massive meteor strike 65 million years ago. Since then, nature has preserved the fossils by freezing, drying, and mineralization.
Scientists must dissolve these fossils and extract their organic compounds to study them. One such compound is heme which occurs in all vertebrate animals. Heme is a substance found in soft tissue like organs and blood vessels. This compound’s presence in dinosaur fossils indicates that they had blood vessels.
Hemoglobin (the protein that carries oxygen in your blood) uses iron to bind to oxygen and carry it throughout your body. Iron is available as an oxygen carrier because it has a high affinity for oxygen molecules. It can also be toxic when present at high concentrations or binds to other molecules that would benefit you.
Scientists have created a chemical indicator dye for iron by attaching it to an organic molecule called porphyrins. Many organisms, including plants and animals, produce substances as part of their metabolism.
Biliverdin
Biliverdin is a green bile pigment molecule that showed up when looking for iron at different wavelengths throughout the dinosaur’s fossilized soft tissue.
Dinosaurs have been extinct for millions of years, but now scientists can study them differently. A recent study shows that the biliverdin pigment molecule, which appears in bile and blood, also appears in dinosaur fossils.
Dr. Michael Buckley led the study and published it in Science Advances. He found that biliverdin is present in the fossilized soft tissue of dinosaurs. It’s possible to detect this molecule even when looking at the fossilized dinosaur bones themselves.
Biliverdin is a byproduct of red blood cells when they break down hemoglobin. It’s also produced when iron reacts with oxygen to form ferric iron, which can then combine with CO2 to create carbonic acid. The CO2 then combines with water to form bicarbonate ions found in urine (and thus urine color).
Using different wavelengths of light, researchers could see where biliverdin was present within each sample of dinosaur fossilized soft tissue and bone samples. This process allowed them to see where nature preserved these molecules over time, even when other organic compounds had degraded or completely lost.
Protoporphyrin IX
Protoporphyrin IX is a red iron-containing heme prosthetic group used as a chemical indicator for free iron within the dinosaur fossils. You can break down the life cycle of the Protoporphyrin IX pigment molecule in dinosaurs into three stages:
- The synthesis of protoporphyrin IX is the first stage. It occurs in the cytoplasm of cells or in organelles called mitochondria.
- The reduction of coproporphyrinogen III to form protoporphyrinogen IX is the second stage. This reaction occurs outside of cells or organelles and produces free iron ions (Fe2+). Protoporphyrinogen IX is then transported back into cells or organelles, where it undergoes further reactions to be mainly incorporated into heme proteins such as hemoglobin or myoglobin.
- The final stage involves the oxidation of an enzyme called ferrochelatase.
Melanin
Melanin is a pigment molecule discovered in the fossilized skin of dinosaurs, and its color can vary by species. It’s also found in the fossilized skin of dinosaurs, and it’s been commonly found to have a wide range of colors.
Dinosaurs have been around for over 200 million years, leaving them with plenty of time to decay. As time passes, bacteria and other microorganisms can break their bodies down, changing their color. When fossilized skin is suddenly exposed to oxygen, it turns brown or black as it ages. We’ve seen fossils from many different browns, black, or even red species.
The shape and size of melanin molecules can vary widely by species. Even within a single species’ skin pigmentation may change depending on where it lives. For example:
- Dinosaurs living in tropical climates tend to have darker colored skin than those living in temperate regions. They need more protection from UV rays from the sun when they’re out in the open air during daylight hours.
- Some dinosaurs had dull colors on their bodies to camouflage themselves from predators.
2. Proteins
Proteins are chains of amino acids. There are also 20 amino acids in all proteins, but their sequence is different. Organic molecules, such as keratins and collagens, are proteins found in the skin of the dinosaur fossils.
Collagens
Collagens protein molecules were mostly found within the soft tissue of dinosaur fossils. They aid in the structure-forming abilities of cells. Collagens consist of three parts: collagen proteins, proline, and hydroxyproline. These proteins are often found in most animals, but their composition varies.
Collagens are a major component of soft tissue in dinosaur fossils. They play an important role in the life cycle of these fossils by aiding in the preservation process. Proteins such as collagens are resistant to destruction by heat or other means such as radiation. The structure formed by these substances allows them to preserve their original shape even after millions of years.
Synthesis Stage: During this stage, cells synthesize collagen proteins. The low molecular weight amino acids are first assembled into procollagen chains by hydroxylating lysine side chains. Many procollagen chains are then assembled to form collagen fibrils.
The fibrils are cross-linked together by lysyl oxidase, which catalyzes the formation of interchain covalent bonds between lysine residues at the N-terminal end of one strand and another amino acid residue at the C-terminal end of another strand.
Degradation Stage: An enzyme called collagenase degrades the collagen molecule. Collagenase, an enzyme that breaks down collagen and converts it into smaller molecules called peptides, is then recycled back into new collagen molecules through a process known as resynthesis or biosynthesis.
Recycling Stage: The body can recycle broken collagen by sending the peptides to an active site within a lysosome cell. The enzymes must first bind to other components in the cell.
One interesting fact about the collagens proteins molecule in dinosaurs is that it does not end at death. It simply continues into another organism’s body, forming new cells or tissue depending on its location.
Keratins
Keratin protein molecules were also found within dinosaur fossils’ soft tissue, which is key to hair growth, strength, and protection. It is also present in the eggshells of birds. Keratin is a key component of organic compounds present within dinosaur fossils, and it has been commonly found in all types of dinosaur species.
To understand how nature can preserve keratin in fossils so long after their deaths, scientists need to examine keratin proteins’ structure and chemical makeup. Keratin proteins consist of several amino acids that combine to form polypeptide chains. These chains fold into sheets or coil tightly into spirals known as alpha helixes or beta-pleated sheets.
The amino acids that form keratin proteins are either cysteine-rich or non-cysteine-rich. It depends on whether they contain cysteines (amino acids with sulfur atoms).
The stability of keratin molecules depends on their composition; the more acidic amino acids tend to break down more rapidly than those with basic side groups such as lysine and arginine (which have amide groups).
Disulfide bridges stabilize keratins. In addition to stabilizing the structures of keratins, disulfide bonds also function as bridges between adjacent strands through covalent bonding between cysteine residues.
3. Metabolic Intermediates
Metabolism is the chemical processes inside living cells to sustain life, including cell division and growth. In biochemistry, metabolism refers to all chemical reactions in a cell. It includes catabolism and anabolism. These processes break down molecules and form molecules to maintain life and support growth.
Ketone Bodies
The ketone bodies were first identified when scientists found that they were present in the fossils of dinosaurs. Scientists discovered it while studying a dinosaur fossil preserved inside a rock for over 100 million years. They found two different types of ketone bodies present in this particular fossil. It includes alpha-hydroxybutyrate and acetoacetate.
The reason is that the body produced two types of ketone bodies when insulin was absent during ketogenesis. This process happens when someone suffers from diabetes, obesity, and alcohol drinks excessively.
Excessive fatty acids in the bloodstream must produce ketone bodies; otherwise, they will not form. They can also form if someone has been fasting for long periods or does not eat enough carbohydrates. The body would normally convert it into glucose.
During our metabolism, we rely on oxygen to produce energy. We also rely on glycolysis, breaking glucose into pyruvate and ATP (adenosine triphosphate).
The process of glycolysis produces three molecules called ketone bodies (acetoacetic acid, beta-hydroxybutyric acid, and acetone). The body releases ketone bodies into the bloodstream, and one of its many functions is as an energy source for other body parts. For example, your muscles will use these ketone bodies to fuel their activity if you’re exercising.
It is exactly what happened with dinosaurs. They used their ketone bodies to fuel their activities when they were alive. Sometimes it included running from predators or fighting over territory.
4. Lipids
Lipids include waxes (long-chain alcohols), steroids (related to steroids), alcohol sterols, fats (triacylglycerols), and phospholipids (fatty acid glycerol esters).
Waxes
As we all know, dinosaurs are extinct. But you may not have heard that their fossils are still around—and they’re very useful in teaching us about the chemistry of organic compounds.
A recent study has examined the chemical composition of dinosaur bones. It reveals that the fossils contain a surprising number of lipids. Dinosaurs are most famous for their size (and having feathers), but it’s not well-known that they were also pretty big and fat.
The researchers used a Raman spectroscopy technique to investigate the lipid content of dinosaur bones. They found that they could identify two types of lipids: waxes and esters. Waxes are long-chain alcohols with fatty acids attached. Esters are the combination of two molecules—alcohol and fatty acid-forming an ester bond between them.
These lipids make up part of what’s known as “cuticle.” It is a waterproof coating on plants like leaves and stems that prevents excessive water loss. These lipids aren’t just interesting because they come from dinosaurs—they’re interesting because they help us understand how plants work.
Steroids
Steroids are a group of organic compounds composed of four fused rings. The class consists of cholesterol, bile acids, sex hormones, and vitamin D. You can find steroids in many different places and organisms. It includes plants, animals, and bacteria.
The existence of steroids in a fossil indicates the presence of lipids in the organism’s body. Lipids are insoluble in water, so fossils would not have been well preserved through fossilization unless there was some chemical reaction to make them more soluble.
In addition to steranes and their derivatives, other compounds that can infer the existence of anaerobic metabolism (in which oxygen is not present) include sterols such as cholesterol and ergosterol (a type of steroid found in yeast). These compounds only form under anaerobic conditions. They need molecular oxygen for synthesis. If no oxygen were available, anaerobic conditions could not have produced these molecules.
The presence of steranes suggests that dinosaurs could produce steroid hormones. It does not necessarily mean that they lived under anaerobic conditions or had any respiratory system. In this case, steranes can also form through abiotic processes. 
Alcohols (Sterols)
Alcohols are one of the most common organic compounds found in fossilized dinosaur bones. Steroids are a group of lipids that have a characteristic ring structure. They are amphipathic, meaning that one end is polar and the other is non-polar.
The polar end contains an oxygen atom, and the non-polar end has carbon chains. This feature makes them amphipathic lipids, which means they can interact with water and fat.
The main difference between plant and animal sterols is that animals synthesize a molecule with a hydroxyl group on the A ring, polar. It means that it will dissolve easily in water, which would have been very important for dinosaurs because they lived in a humid environment.
The critical thing to remember about steroids is that they are classified as sterols. The classification of steroids depends on their structure and function. Plants have phytosterols, while animals have zoosterols.
The difference between phytosterols and zoosterols is that zoosterols contain cholesterol or steroid molecules in their bodies. In contrast, phytosterols do not have cholesterol or steroid molecules in their bodies.
Dinosaurs had cholesterol and steroid molecules in their bodies, similar to those in modern reptiles. All living organisms contain steroids. Sterol molecules were probably one of the first molecules ever produced by life.
Fats (Triacyglycerols)
Fats are a key component of living tissues, and they occur in all types of fossils. Fats are one of the most common organic compounds in fossils. Fat is a triacylglycerol molecule (TAG) consisting of three fatty acids and one glycerol molecule. TAGs usually have a solid consistency at room temperature, but they are easily melted or solubilized by heat or pressure.
When dinosaurs lived on earth, their bodies contained fats and oils, part of their skin, muscle tissue, and organs. Just like today’s animals, dinosaurs’ bodies had to be able to store energy to survive long periods without food or water. Their bodies’ fats helped them store energy as triglycerides (TAGs) instead of glucose or glycogen (carbohydrates).
The type of fat that dinosaurs had in their bodies depends on their cell membranes’ types of fatty acids.
- Saturated fatty acids have no double bonds between the carbon atoms of their molecules.
- Unsaturated fatty acids have double bonds between the carbon atoms of their molecules.
- Trans fats contain two or more hydrogen atoms bonded to each carbon atom in the chain instead of an alkane.
Dinosaurs are more similar to us than you think. In a study of the cell membranes of reptiles and birds, scientists have found that dinosaurs use the same fat as modern birds, so they might even eat like them.
Final Thoughts
It’s important to remember that scientists are still working to tease out the mysteries of dinosaur biology. Some things will remain unknown for some time. We can be confident that future scientists will continue to study fossils in hopes of uncovering new secrets about the life and death of prehistoric animals.
The organic compounds found in dinosaur fossils are similar to those found in living organisms. They may indicate that dinosaurs had life processes like those of modern-day animals. Studying these organic compounds can reveal how dinosaurs lived on earth millions of years ago. This study will help us understand their evolution, behavior, and ecology.
