AP Biology class blog for discussing current research in Biology

Tag: paleontology

After 50 Years, Ancient Fish Finally Named

Tiktaalik roseae life restor

The Australian Outback is one of the most hostile environments on planet earth. Covering a land mass of nearly twenty two times the size of the United Kingdom, this dry landscape is a formidable and unforgiving adversary for the species that have adapted to inhabit it. But The Outback wasn’t always as dry as it is today. Millions of years ago, it was a lush, green biome that had rivers running in all directions. A recent archeological excavation has presented a team of scientists with a unique opportunity to name a fossil fish. Dr. Brian Choo of Findlers University and a team of researchers named the fish Harajicadectes zhumini after developing a more comprehensive understanding of the species. While fragments of Harajicadectes were discovered in 1973, a nearly complete specimen was unearthed by Flinders University in 2016, when they began constructing a comprehensive profile of the species.

By observing the skeletal remains, the team was able to reconstruct a hypothesized anatomy of the animal. One of its striking features was a series of large openings at the top of its head. “These spiracular structures are thought to facilitate surface air-breathing, with modern-day African bichir fish having similar structures for taking in air at the water’s surface,” commented Dr. Choo. In light of these findings, the team began to consider how the supplementary breathing apparatuses contribute to our evolutionary heritage. “The ability to supplement gill respiration with aerial oxygen likely afforded an adaptive advantage,” added Professor Long. Harajicadectes is a member of those intrepid water dwellers who brought life to land. Elpistostegalians gave way to limbed tetrapods in the evolutionary family tree.

The evolutionary edge that supplementary breathing gave Harajicadectes is not to be underestimated. It is widely understood that oxygen sustains life, but its immense significance can only be realized when looking at the molecular level of respiration. Mitochondria are one of the most ancient organelles and, according to the endosymbiont theory, preceded eukaryotic cells as aerobic bacteria. In the final and most powerful stage of Cellular respiration – oxidative phosphorylation – oxygen plays an essential role in ensuring that ATP is churning. Oxidative phosphorylation takes place in the mitochondrial inner membrane, where proton pumps transport hydrogen protons from the mitochondrial matrix to the intermembrane space where a gradient builds. Then, through simple diffusion, protons cross through the ATP synthase complex back into the matrix where they bind with O2 molecules, forming H2O as a byproduct. If Harajicadectes didn’t have access to oxygen on land, it would have only been able to leave the water for brief periods of time. This would have greatly reduced its competitive advantage on the shores and reduced the likelihood of limbed tetrapod evolution. 

I think the field of paleontology is an underappreciated field of biology and science. Just as the field of history provides context for the problems of today, paleontology better helps modern biologists understand how, when, and why species evolve as they do. This naming of the animal has been fifty years in the making, but thanks to the team of Australian scientists, we understand our evolutionary beginnings slightly better. I find the mapping of ancient biomes fascinating, and as more advanced chemistry develops, maybe one day scientists will be able to bring these prehistoric animals back to life. 

Love in the World of Paleontology: The Story of Annie Alexander

This is not just a biology story

Annie Montaque Alexander was born on December 29th, 1867. In 1901, she found herself attending a lecture by John C. Merriam on paleontology at Berkeley University. She was hooked instantly and requested to join the fossil explorations.

Annie’s life is defined by traveling. She was an outdoors person and fossil exploration was like a gold mine for her. She took part in explorations to Fossil Lake, Oregon (1901), Shasta County, California (1902 & 1903), and the West Humboldt Range in Nevada (1905). This last expedition discovered a large amount of Triassic ichthyosaur skeletons, including some of the largest in the world. 

An ichthyosaur is any member of an extinct species of aquatic reptiles. They are similar to porpoises in appearance and are distant relatives of lizards and snakes. They are highly specialized, but not dinosaurs. Their remains span almost the entire Mesozoic Era, but are abundant and diverse during the Triassic and Jurassic periods.

She took part in all the hard work and hardships that come with field work, as well as cooking the meals for the trip. These expeditions, as a part of her agreement with Merriam, were all expeditions she financed. 

Her interests were not limited to paleontology. In 1908, Annie helped establish the Museum of Vertebrate Zoology and made up the difference when State appropriations for its construction fell short. She did this all before she had the right to vote. That’s crazy!

Annie also took part in many trips to Alaska, where she collected mammal skulls. This is where she discovered a new subspecies of grizzly bear, named Ursus alexandrae after her. 

Also in 1908, Annie met and began traveling with Louise Kellogg. Annie and Louise would live and travel together until Annie’s eventual death in 1950.

Same sex marriage was not legal until 2015. Annie and Louise were a couple living in what is referred to as a “Boston Marriage”. A “Boston marriage” is a term for women living in a marriage-like relationship without any male support. While not all “Boston Marriages” are lesbian relationships in a sexual sense, the term is better described as ‘domestic partnerships’. It is derived from Henry James’s 1886 book detailing a marriage-like relationship between two women. Despite all of this, it’s obvious that Annie and Louise loved each other.

Annie and Louise found themselves on adventures in California, Nevada, New Mexico, Utah, Colorado, Idaho, and Arizona. The heat could get as high as 136 degrees! Crazy to think about heat like that in cold like this!

Annie and Louise collected over twenty thousand specimens of animals, plants, and fossils for the museums. Like Ursus alexandrae, many of the new species were named after Annie, including Hydrotherosaurus alexandrae (Cretaceous plesiosaur), Swollenia alexandrae (grass species), Shastasaurus alexandrae (Triassic ichthyosaur), Alticamelus alexandrae (Miocene camel), and more. Oh, what I’d give to have a dinosaur named after me! Laurasaurus pasqualae. Pretty awesome!

She followed the field and laboratory work of the paleontologists at Berkeley closely and maintained a close relationship with Dr. Merriam and his successors throughout her life. 

The 1900s was not a pleasant time for women in the STEM field and Annie knew this. Even if the only thing separating men from women is a y-chromosome, many people looked down upon women, and still do today. Annie repeatedly complained about the need for a fireproof building for the fossil collections and reestablish a strong paleontology program. She never gave up on her goals. Yet, she often found herself negotiating her pleas. Her gender, as well as the untimely recent depression, led to complications. Still, she never gave up on what she was passionate about and that is admirable.

The research and specimens founded by Annie and Louise contributed to long-term data today. Both Annie and Louise ignored society’s attempts to hold them down and did what they loved in their life. No one could stop them.

I think Annie Alexander is an extremely interesting person. I’ve never heard of her before I did my research. She appreciated scientific research and understood the important questions and problems for studying, despite not being a research scientist herself. She properly documented and preserved her specimens to keep their scientific value. She is a great judge of character and is extremely loyal to the people she trusts. Louise was a lucky lady to have Annie in her life. We all are lucky to have Annie as a person to look up to.

New Prehistoric Fish Discovery to Change How We View Our Evolutionary History?

a reconstruction of Entelognathus Primordialis

Prior to now, it has been accepted as common knowledge that cartilaginous fish predate bony fish in the ancient parts of the evolutionary family tree. As a result, it has been generally assumed that the earliest fish with jaws would have something fairly closely resembling that of a shark, as sharks are accepted to be on of the most ancient of vertebrates. However, the recent discovery of Entelognathus Primordialis in China may cause us to question these long held beliefs and assumptions.


This armored, toothless fish, may be up to 419 Million years old. Making it one of, if not the earliest vertebrate to be discovered to date, and it’s discovery throws a wrench in our image of what our prehistoric ancestors looked like. Entelognathus, rather than being a sleek, sharklike cartilaginous fish, is bony, with many small plates making up it’s skull and jaw. This skeletal template is something found in all land-dwelling vertebrates in modern day, leading scientists to theorize that rather than bony skeletons evolving from cartilaginous ones. it may have happened the other way around. Making our armored ancestors potentially more ancient than sharks’ more scaly predecessors.


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