Text 1
The land that became Grande Terre island split from remnants of the former supercontinent Gondwana approximately 80 million years ago, carrying Gondwanan biota with it, and experienced periodic submersion until 37 million years ago. Some researchers posit that the island’s current biota includes members of Gondwanan clades (i.e., clades predating the split) that persisted by seeking temporary refuge on nearby islands during submergence events.
Text 2
In a recent study, Anna Papadopoulou et al. found that the crown age—the age of the most recent common ancestor of all species in the clade (i.e., the clade’s founder)—is 59.9 million years for Grande Terre’s clade of leaf beetles. Most of the island’s extant biota belong to clades with younger crown ages, however: Igor V. Bartish et al. found that the crown age of Grande Terre’s clade of Pycnandra plants is 22.9 million years, for example.
Taken together, Text 1 and Text 2 best support which statement about the clades of leaf beetles and Pycnandra plants on Grande Terre?
Explanation
Context: Text 1 explains that some researchers believe Grande Terre's current plants and animals descend from clades that existed on Gondwana before Grande Terre split off 80 million years ago, surviving submergence periods by refuging on nearby islands. Text 2 presents Papadopoulou et al.'s finding that the crown age of Grande Terre's leaf beetle clade is 59.9 million years — younger than Grande Terre's split from Gondwana (80 million years ago), and also younger than Grande Terre's full emergence (37 million years ago). A separate finding shows the Pycnandra plant clade has a crown age of about 22.7 million years — also younger than both dates.
Answer: C) Neither the clade of leaf beetles nor the clade of Pycnandra plants originated on Gondwana.
Why? Text 1's "some researchers" view requires clades to predate the Gondwana split (80 million years ago). But both clades in Text 2 are younger than this date (59.9 million years and 22.7 million years respectively) — meaning neither could be a Gondwanan survivor. C follows directly from combining both texts.
Traps:
- A) "The clade of leaf beetles originated before Grande Terre split from Gondwana, but the clade of Pycnandra plants did not" → leaf beetle crown age (59.9 million years) is younger than the Gondwana split (80 million years), so leaf beetles did NOT originate on Gondwana
- B) "The clade of leaf beetles must have originated on Gondwana, but the clade of Pycnandra plants did not" → same error; 59.9 million years is after the 80 million year Gondwana split
- D) "Both the clade of leaf beetles and the clade of Pycnandra plants originated on Gondwana" → both crown ages are younger than 80 million years; neither originated on Gondwana