ACADEMIC READING
Answer key at the end.
Mammal Ancestors Laid Eggs
A remarkable fossil discovery is shedding new light on one of Earth’s most extraordinary survival narratives while resolving a long-standing scientific enigma. Lystrosaurus, a resilient, plant-eating precursor to mammals, rose to ecological dominance after the End-Permian Mass Extinction, a catastrophic event that eradicated most life. Despite extreme heat, drought, and environmental instability, this species not only survived but proliferated.
Recent research published in PLOS ONE documents the discovery of a 250-million-year-old egg containing a Lystrosaurus embryo. Led by Julien Benoit, Jennifer Botha, and Vincent Fernandez, the international team confirmed that early mammal ancestors reproduced by laying eggs—settling a question that had persisted for decades. The rarity of this fossil is largely due to its soft shell, which, unlike the hardened eggs of dinosaurs, typically decomposes before fossilization.
Advanced synchrotron X-ray scanning at the European Synchrotron Radiation Facility enabled researchers to examine the specimen in exceptional detail. The imaging revealed an undeveloped jaw structure, indicating the embryo had not yet reached a stage where it could feed independently.
Further analysis suggests that Lystrosaurus produced relatively large, yolk-rich eggs. This adaptation likely supported rapid, independent development after hatching, eliminating the need for parental care. Such reproductive efficiency, combined with accelerated growth, allowed the species to thrive in harsh post-extinction environments. Ultimately, this discovery not only clarifies the reproductive biology of early mammalian ancestors but also highlights how adaptability and strategic reproduction can determine survival in periods of global ecological crisis.
What does the author imply about the discovery of Lystrosaurus?
A. It was a discovery scientists were expecting to make
B. It has indicated the location of new sites to dig for fossils
C. It may be able to solve an upcoming global ecological crisis
D. It has settled a debate in the scientific community
The word “enigma” in the first sentence is closest in meaning to:
A. debate
B. mystery
C. competition
D. dispute
According to the passage, why are Lystrosaurus embryo fossils rare?
A. They are difficult to find at most archaological sites
B. They disappear under layers of sediment
C. They break down before they can become fossils
D. They become too hardened to be identified correctly
According to the passage, how is the yolk of an egg useful for embryos?
A. It gives animals more nutrients than mammalian milk
B. It provides the embryo with enough vitamins for brain development
C. It allows the embryo to begin its life independently
D. It allows the embryo to survive major extinction events
Which of the following is NOT true about Lystrosaurus?
A. They went extinct 250 million years ago
B. They were herbivores
C. They were able to survive harsh conditions
D. They did not require any parental care after hatching
Answer Key
D, B, C, C, A
Answer key at the end.
Mammal Ancestors Laid Eggs
A remarkable fossil discovery is shedding new light on one of Earth’s most extraordinary survival narratives while resolving a long-standing scientific enigma. Lystrosaurus, a resilient, plant-eating precursor to mammals, rose to ecological dominance after the End-Permian Mass Extinction, a catastrophic event that eradicated most life. Despite extreme heat, drought, and environmental instability, this species not only survived but proliferated.
Recent research published in PLOS ONE documents the discovery of a 250-million-year-old egg containing a Lystrosaurus embryo. Led by Julien Benoit, Jennifer Botha, and Vincent Fernandez, the international team confirmed that early mammal ancestors reproduced by laying eggs—settling a question that had persisted for decades. The rarity of this fossil is largely due to its soft shell, which, unlike the hardened eggs of dinosaurs, typically decomposes before fossilization.
Advanced synchrotron X-ray scanning at the European Synchrotron Radiation Facility enabled researchers to examine the specimen in exceptional detail. The imaging revealed an undeveloped jaw structure, indicating the embryo had not yet reached a stage where it could feed independently.
Further analysis suggests that Lystrosaurus produced relatively large, yolk-rich eggs. This adaptation likely supported rapid, independent development after hatching, eliminating the need for parental care. Such reproductive efficiency, combined with accelerated growth, allowed the species to thrive in harsh post-extinction environments. Ultimately, this discovery not only clarifies the reproductive biology of early mammalian ancestors but also highlights how adaptability and strategic reproduction can determine survival in periods of global ecological crisis.
What does the author imply about the discovery of Lystrosaurus?
A. It was a discovery scientists were expecting to make
B. It has indicated the location of new sites to dig for fossils
C. It may be able to solve an upcoming global ecological crisis
D. It has settled a debate in the scientific community
The word “enigma” in the first sentence is closest in meaning to:
A. debate
B. mystery
C. competition
D. dispute
According to the passage, why are Lystrosaurus embryo fossils rare?
A. They are difficult to find at most archaological sites
B. They disappear under layers of sediment
C. They break down before they can become fossils
D. They become too hardened to be identified correctly
According to the passage, how is the yolk of an egg useful for embryos?
A. It gives animals more nutrients than mammalian milk
B. It provides the embryo with enough vitamins for brain development
C. It allows the embryo to begin its life independently
D. It allows the embryo to survive major extinction events
Which of the following is NOT true about Lystrosaurus?
A. They went extinct 250 million years ago
B. They were herbivores
C. They were able to survive harsh conditions
D. They did not require any parental care after hatching
Answer Key
D, B, C, C, A
