We can’t drive across a green meadow in a Jeep and take off our sunglasses with a trembling hand while seeing with our own eyes a Brachiosaurus alive and kicking. At least we can’t for now. As long as we don’t have our particular Dr. Hammond in real life, the closest thing to a Jurassic Park is a farm.
Yes, it may not sound that spectacular or glamorous, but it is extremely interesting to know that the closest modern species to Tyrannosaurus rex are the chicken and the ostrich.
what science says
Chris Organ, a postdoctoral researcher in organic and evolutionary biology at Harvard University, led research whose results were published in the journal Science. In 2003, John Horner , a paleontologist at the Museum of the Rockies, found remains of a 68-million-year-old Tyrannosaurus rex in the northern United States, between the states of Wyoming and Montana. Two years later, Mary H. Schweitzer of the University of North Carolina discovered that a thin layer of tissue had been preserved on the specimen’s femur. The discovery was not enough to recover DNA from the bone, but it was possible to extract protein sequences that have turned out to be valuable evidence to work on. The scientists compared a protein preserved in the collagen of the fossil’s femur with 21 species of modern reptiles and birds. The compared genetic sequences confirmed that chickens and ostriches descended from the Tyrannosaurus. These birds would be the closest to the famous bipedal predatory dinosaur and, further away, the current crocodiles would follow.
Therefore, far from being able to cross long meadows and forests full of extinct species, today, the closest experience to the one lived by Dr. Alan Grant and Dr. Ellie Sattler in Jurassic Park would be on a farm . Specifically, in a chicken or ostrich pen, whose farms experienced a boom in Spanish territory at the beginning of the century with up to a thousand farms.
The same method was used with some protein sequences extracted from mastodon bones between 160,000 and 600,000 years old. The results concluded that current elephants are direct descendants of those prehistoric mammals. An investigation that confirmed what paleontologists had already predicted when comparing the skeletons of both species.
Difficulties in the investigation
The investigation had a high degree of difficulty due to the little material that Organ’s team had. With just 89 amino acids from Tyrannosaurus, it is impossible to recreate a more complete phylogenetic tree for this species of dinosaur. But, without a doubt, we are facing a milestone, since it is the first use of molecular data to place a non-avian dinosaur in a phylogenetic tree in order to trace the evolution of the species. An approach to evolutionary history that is inspiring and brings with it results as curious as the one we present here. “Although we only had six peptides, just 89 amino acids, from T. rex, we were able to establish these relationships with a relatively high degree of support. With more data, we would probably see the T. rex branch in the phylogenetic tree between alligators, chickens and ostriches, although we cannot resolve this position with the currently available data”, argued Chris Organ.
A study prior to that of Organ already pointed out how to obtain protein from the collagen of a rex . That previous article, also published in the journal Science, had John M. Asara and Lewis C. Cantley, from the Beth Israel Deaconess Medical Center and Harvard Medical School, as team leaders. By then they managed to capture and sequence collagen protein fragments from T. rex for the first time. Following that research, Organ, Asara and their colleagues used sophisticated algorithms to compare the collagen protein to other species. This is how they have discovered that those Cretaceous animals can be better associated with modern birds than with reptiles. “We determined that T. rex did, in fact, cluster with birds (ostrich and chicken) better than any other organisms we studied. We also show that it groups better with birds than with modern reptiles, such as alligators and green anole lizards,” Asara said of the study results.
from teeth to beak
It is clear that a common chicken may not impress as much as a Tyrannosaurus rex roaring or attacking a huge prey. But what is still fascinating is observing and studying the evolution of species over millions of years. Thus, little by little, we are completing the gigantic puzzle that shows us how such a large and ferocious predator can have a totally domesticated relative that does not exceed half a meter in height.
References:
Asara, JM et al. 2007. Protein Sequences from Mastodon and Tyrannosaurus Rex Revealed by Mass Spectrometry. Science 316, 5822. DOI: 10.1126/science.1137614.Organ, C.L et al. 2008. Molecular Phylogenetics of Mastodon and Tyrannosaurus rex. Science 320, 5875. DOI: 10.1126/science.1154284.
