In a groundbreaking discovery, bone cavities referred to as air sacs were identified in the precursors to long-necked dinosaurs, dating back approximately 225 million years. This evidence was found in a specimen from the state of Rio Grande do Sul in South Brazil. Contrary to prevailing scientific theories, the evolution of these air sacs did not follow a straightforward trajectory. The research was credited to Márcio L. Castro.
A newly discovered link has been identified that connects early dinosaurs, whose sizes ranged from just a few centimeters to up to 3 meters, with their later gigantic counterparts, capturing the public’s fascination due to their immense sizes.
Macrocollum itaquii, excavated from the Agudo region in the Rio Grande do Sul state and dating back to 225 million years ago, stands as the most ancient known dinosaur possessing these air sac structures.
These bone cavities, still found in modern-day birds, facilitated increased oxygen intake, thermoregulation, and resilience to the challenging environmental conditions of their epoch. Such features contributed to the evolution of colossal dinosaurs like Tyrannosaurus rex and Brachiosaurus.
The research was detailed in an article in the journal Anatomical Record, and two authors were scholars supported by FAPESP at the State University of Campinas (UNICAMP) in São Paulo.
“Reduced bone density due to the presence of air sacs enabled these creatures to grow to lengths exceeding 30 meters,” stated Tito Aureliano, the paper’s lead author. His PhD research at the Institute of Geosciences (IG-UNICAMP) encompassed this study.
According to Aureliano, “M. itaquii was the most sizable dinosaur of its era, measuring approximately 3 meters in length. This substantial increase in size, relative to dinosaurs a few million years prior, was notably facilitated by these air sacs.”
The research is a component of the project “Taphonomic landscapes”, underwritten by FAPESP. Taphonomy pertains to the study of the decay and fossilization of organisms in the paleontological record.
Fresia Ricardi-Branco, the project’s principal investigator and a faculty member at IG-UNICAMP, noted that “this dinosaur was among the earliest to inhabit the Earth during the Triassic period. The adaptation involving air sacs conferred growth and environmental resilience advantages during this period and beyond, to the Jurassic and Cretaceous epochs. It led to a more rapid diversification compared to other organism groups like mammals.”
In an earlier study by the group, it was indicated that the most primitive fossils did not possess air sacs, suggesting that this trait evolved independently at least three times.
M. itaquii was identified as a bipedal sauropodomorph and served as an ancestor to massive quadrupeds with comparatively small heads and long necks.
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Nonlinear Evolution
Previous to this discovery in M. itaquii, vertebral cavities were understood to be composed of either camerate or camellate tissue. The research team, however, discovered “internal pneumatic chambers” that were neither of the two known types but exhibited an intermediate texture. These new structures were termed “protocamerate.”
“The prevalent hypothesis had been that air sacs initially developed as camerae and later evolved into camellae. Our findings challenge this, suggesting an alternative origin,” commented Aureliano.
Moreover, the discovery impacted prevailing theories regarding the evolutionary timeline of air sacs. Previous analyses proposed that these structures initially appeared in the abdominal region, later appearing in the cervical region around 190 million years ago. Contrary to this, evidence of air sacs in the cervical and dorsal regions was found in M. itaquii, without any in the abdominal region.
Aureliano concluded, “The evolutionary process that led to the current air sac system, spanning from the neck to the tail, appears to have been a series of exploratory adaptations rather than a linear development.”
This research was financially supported by the São Paulo Research Foundation.
Reference: “The origin of an invasive air sac system in sauropodomorph dinosaurs” by Tito Aureliano, Aline M. Ghilardi, Rodrigo T. Müller, Leonardo Kerber, Marcelo A. Fernandes, Fresia Ricardi-Branco, and Mathew J. Wedel, published on 27 March 2023 in The Anatomical Record. DOI: 10.1002/ar.25209.
Frequently Asked Questions (FAQs) about Dinosaur Air Sacs
What is the significance of the discovery of air sacs in ancient dinosaurs?
The discovery of air sacs in ancient dinosaurs is significant because it challenges existing theories about their evolution. It suggests that these air sacs played a crucial role in facilitating rapid diversification and size growth in dinosaurs, contrary to previous linear evolutionary models.
How old is the specimen in which the air sacs were discovered?
The specimen in which the air sacs were discovered dates back approximately 225 million years.
What were the functions of these air sacs in dinosaurs?
These air sacs served several functions, including increasing oxygen intake, aiding in thermoregulation, and enabling dinosaurs to withstand the challenging environmental conditions of their era. They also contributed to the growth of gigantic dinosaurs.
Who conducted the research, and where was it published?
The research was conducted by a team of scientists, including Tito Aureliano and Fresia Ricardi-Branco, and it was published in the journal “The Anatomical Record.”
How does this discovery impact previous theories about the evolution of air sacs in dinosaurs?
This discovery challenges previous theories by suggesting that air sacs did not follow a linear evolutionary path, as previously believed. Instead, it indicates that there were exploratory adaptations in the development of these structures.
What was the largest dinosaur of its time mentioned in the article, and how big was it?
The largest dinosaur of its time mentioned in the article is “Macrocollum itaquii,” which measured approximately 3 meters in length. This was a significant size increase compared to dinosaurs just a few million years prior.
How were the air sacs in this specimen different from those previously known in dinosaurs?
The air sacs in this specimen were different from those previously known because they exhibited a new type of tissue with an intermediate texture, which the researchers termed “protocamerate.” This challenged the previous understanding of air sac structure in dinosaurs.
What funding supported this research?
The research was financially supported by the São Paulo Research Foundation (FAPESP).
Why is the discovery of air sacs in dinosaurs important for our understanding of their evolution?
The discovery of air sacs in dinosaurs is important because it sheds light on how these creatures were able to grow to such gigantic sizes and adapt to their environments. It also provides insights into the non-linear nature of evolutionary processes in these ancient creatures.
More about Dinosaur Air Sacs
- The Anatomical Record – The journal where the research on air sacs in dinosaurs was published.
- São Paulo Research Foundation (FAPESP) – The organization that provided funding for the research.
- Triassic period – Information about the geological period when dinosaurs like Macrocollum itaquii lived.
- Tyrannosaurus rex – Information about the famous dinosaur mentioned in the article.
- Brachiosaurus – Information about another dinosaur mentioned in the article.
- Evolutionary biology – Background information on the field of evolutionary biology, which plays a role in understanding the dinosaur air sac discovery.
4 comments
Wow, dinos with air sacs? Who knew?! This is sum crazy sci stuff!
Imp implications for dinosaur evolution. fascinating, want more info!
What’s the ROI on dino air sacs? Joking, but seriously, interesting read.
Dinos & crypto, my two fav topics. didn’t see that coming. Cool article!