From the Wu et al. 2012 abstract:
“The timing of the origin and diversification of rodents remains controversial, due to conflicting results from molecular clocks and paleontological data. The fossil record tends to support an early Cenozoic origin of crown-group rodents. In contrast, most molecular studies place the origin and initial diversification of crown-Rodentia deep in the Cretaceous, although some molecular analyses have recovered estimated divergence times that are more compatible with the fossil record. Here we attempt to resolve this conflict by carrying out a molecular clock investigation based on a nine-gene sequence dataset and a novel set of seven fossil constraints, including two new rodent records (the earliest known representatives of Cardiocraniinae and Dipodinae). Our results indicate that rodents originated around 61.7–62.4 Ma, shortly after the Cretaceous/ Paleogene (K/Pg) boundary, and diversified at the intraordinal level around 57.7–58.9 Ma.”
The Wu et al. cladogram
correctly derives placentals from marsupials, but employs Monodelphis as the outgroup rather than the Caluromys, as recovered by the large reptile tree (LRT, 1360 taxa, subset Fig. 1). The Wu et al. cladogram incorrectly nests horses with carnivores in the invalid clade, Laurasiatheria. The next split produces the clade Primates + Glires, omitting the clade Volitantia. Within the clade Glires, only two extant lagomorphs are employed, omitting 16 tree shrews, false tenrecs and many fossil taxa that preceded them as recovered by the LRT. Within the clade Rodentia, the large extant clades within the Wu et al. study matched the LRT, but the Wu et al. study omitted all fossil taxa, including plesiadapiformes, multituberculates, carpolestids and the extant aye-aye (Daubentonia).
Contra Li et al. 1987 and Wu et al. 2012,
rodents and rabbits diversified in the Early Jurassic, as we learned earlier, because their ancestors, the multituberculates and Henkelotherium (related to living pikas, Fig. 1), appear in the Middle and Late Jurassic. DNA does not work in deep time studies.
Li C-K., Wilson RW, Dawson MR, Krishtalka L 1987. The Origin of Rodents and Lagomorphs. In: Genoways H.H. (eds) Current Mammalogy. Springer, Boston, MA
Wu S et al. (8 co-authors) 2012. Molecular and Paleontological Evidence for a Post-Cretaceous Origin of Rodents. PLoS ONE 7(10): e46445. https://doi.org/10.1371/journal.pone.0046445