Chapter 1: The Intrigue of Martian Fossils

As a paleontologist, my inbox often contains unusual messages. Unlike most, mine includes dubious invitations from fake journals promising to enhance their publications with my crustacean fossil research. So, when an email stated that fossils had been discovered on Mars, my initial reaction was to question its legitimacy.

However, this was no joke. The email came from a diverse group of scientists—geologists, astronomers, neurobiologists, and a few paleontologists—seeking insights from my colleague, Joe Moysiuk, about some newly released images from NASA's Curiosity rover.

At that time, both Joe and I were PhD candidates at the Royal Ontario Museum, investigating the origins of arthropods using 500-million-year-old fossils from the renowned Burgess Shale in British Columbia. The images presented by Curiosity purportedly showcased Martian fossils, many resembling the organisms we study from the Burgess Shale. This proposition was indeed remarkable.

Could Mars have once harbored life forms akin to the tentacled Haplophrentis, a distant ancestor of the shelled brachiopods that once thrived in Earth's oceans?

As Carl Sagan famously remarked, "Extraordinary claims require extraordinary evidence."

Before delving into our response to this inquiry, it’s essential to recognize that the question of whether fossils could be found on Mars is inherently captivating. Despite its average temperature of -60 degrees Celsius (-80 degrees Fahrenheit) and exposure to intense ionizing radiation, Martian conditions may not be as hostile as those of other celestial bodies in our Solar System.

Yet, the geology of Mars tells a different tale. The planet's geological record has been chronicling its history since its formation, revealing a landscape shaped by ancient rivers and containing minerals indicative of past liquid water.

While we are still uncertain about the duration and extent of liquid water on Mars, it is evident that, at some point, Mars and Earth shared similar environments.

Chapter 2: Life’s Possibilities on Mars

Between 4 and 3 billion years ago, both planets might have had abundant liquid water, giving rise to rivers, lakes, and possibly oceans. As Earth was already teeming with bacteria, one must ask: if life thrived on Earth, why not Mars?

Various methods exist for searching for life on Mars, from analyzing biomolecules preserved in rocks to detecting methane, a gas often linked to bacterial activity. To determine if ancient life once existed on Mars, we must embark on a journey to find fossils, similar to our endeavors on Earth.

However, even on our planet, unearthing fossils can be quite challenging. Our museums house countless shells, skeletons, and fossils, yet as paleontologists, we face a harsh reality: these specimens represent only a fraction of all species that have ever existed. The majority never fossilized; their remains succumbed to decomposition or were consumed before geological processes could preserve them.

Just as we ponder how many fossils remain hidden beneath our urban landscapes or oceans, the quest for fossils on Mars faces similar obstacles. During its early days, only microscopic organisms like bacteria existed. Before hard structures like shells or wood appeared, how can we find fossils? Is it even possible to discover fossils of such minute organisms?

It is indeed possible.

Two significant types of fossils shed light on Earth's ancient past: those that preserve bacterial activity and exceptionally preserved fossils.

Today, many bacteria form large colonies that produce protective mucus. Over millennia, this mucus can trap sand and debris, forming distinct layered rocks known as stromatolites. Some stromatolites found along the coasts of Shark Bay in Western Australia are over 3 billion years old.

Bacterial colonies can also create unique burrows and patterns that geological processes alone cannot easily explain. Exceptional preservation, while rare, can yield remarkable insights. For instance, the Gunflint Chert in Canada contains exquisitely preserved microfossils, such as Eoasphaera, a cyanobacteria from 1.8 billion years ago.

Even on Earth, distinguishing these fossils from mere geological oddities can be challenging. Yet, if life ever existed on Mars, these fossils would be our primary evidence. Numerous Martian rocks, especially silica-rich mudstones, hold the potential to contain fossils.

Nonetheless, the authors of the initial email made an even bolder claim. Their study, later published in the Journal of Astrophysics and Aerospace Technology, suggested that many Martian rock formations bore striking resemblances to terrestrial animals. This assertion implies that Martian organisms might have followed a similar evolutionary trajectory as those on Earth, or that both planets exchanged life forms through meteorite impacts.

Currently, we lack definitive evidence of Martian fossils, and a few images from Curiosity are insufficient to substantiate such sweeping claims. Consequently, we declined their invitation to collaborate.

The Pitfalls of Perception

Despite the article’s title, "Fossils on Mars? A 'Cambrian Explosion' and 'Burgess Shale' in Gale Crater?", the authors presented a measured discussion, acknowledging a crucial factor influencing their interpretation: their own biases.

In 1912, British zoologist Randolph Kirkpatrick held a radically different perspective on Earth's geological history. He posited that every rock he examined contained remnants of Nummolites, leading him to conclude that these organisms once dominated the planet. Years later, he retracted his theory, realizing that what he observed was a product of his own mind—an example of “motivated perception.”

Motivated perception is a challenge many researchers face. While paleontology is a well-established field, there are always fossils we grapple with understanding, and our desires can cloud our judgment.

On Earth, rocks undergo numerous transformations—shaped by natural forces, eroded by organisms, compressed by tectonic movements, or melted by volcanic activity. Thus, it’s no surprise that fossils are rare.

However, the geological history of Mars has been relatively stable over the past 3 billion years, possibly preserving its ancient biological history better than Earth has.

Curiosity's images are indeed fascinating. Is Mars on the brink of becoming a hotspot for future Martian paleontologists?

The first video, "Martian Meteorite With Strange Bacterial Structures Finally Explained," explores the intriguing findings from Martian meteorites and their potential implications for life on the red planet.

The second video, "10 Years On Mars (Ep 6): Curiosity Could Have Found Fossils," discusses the discoveries made by the Curiosity rover and their significance in the search for Martian life.