Not exactly, but it does retain primitive reptilian features like the cloaca, and egg-laying. So yes, it provides clues to what early mammals were like, although it's a far-removed lineal descendant of them. It retains some features that we know reptiles have and which we lost.
Archaeopteryx may or may not be on the direct line of modern birds, but it certainly provides clues to the transition of dinosaurs to birds at any rate. IOW, if it's offline, a "great uncle" rather than a grandfather, it's not all that far off.
What you're ignoring: Again and again we see this convergence when we trace dissimilar lines back in the fossil record. They grow similar until you can't tell one from the other anymore, until you have a specimen you don't know what bin to lump it in. It's always a tree, a real tree of descent. Evolution predicts that; creation doesn't. It's always there.
Taxonomy, Transitional Forms, and the Fossil Record.
Moving further up the taxonomic hierarchy, the condylarths and primitive carnivores (creodonts, miacids) are very similar to each other in morphology (Fig. 9, 10), and some taxa have had their assignments to these orders changed. The Miacids in turn are very similar to the earliest representatives of the Families Canidae (dogs) and Mustelidae (weasels), both of Superfamily Arctoidea, and the Family Viverridae (civets) of the Superfamily Aeluroidea. As Romer (1966) states in Vertebrate Paleontology (p. 232), "Were we living at the beginning of the Oligocene, we should probably consider all these small carnivores as members of a single family." This statement also illustrates the point that the erection of a higher taxon is done in retrospect, after sufficient divergence has occurred to give particular traits significance.What would once have been a single family has become several families and even superfamilies. Even as these groups merge together back in the fossil record, the branch they are on (carnivores) merges with the ancestors of modern ungulates.
But you've probably seen that before and just "forgot," right?Figure 10. Comparison of skulls of the early ungulates (condylarths) and carnivores. (A) The condylarth Phenacodus possessed large canines as well as cheek teeth partially adapted for herbivory. (B) The carnivore-like condylarth Mesonyx. The early Eocene creodonts (C) Oxyaena and (D) Sinopa were primitive carnivores apparently unrelated to any modern forms. (E) The Eocene Vulpavus is a representative of the miacids which probably was ancestral to all living carnivore groups. (From Vertebrate Paleontology by Alfred Sherwood Romer published by The University of Chicago Press, copyright © 1945, 1966 by The University of Chicago. All rights reserved. This material may be used and shared with the fair-use provisions of US copyright law, and it may be archived and redistributed in electronic form, provided that this entire notice, including copyright information, is carried and provided that the University of Chicago Press is notified and no fee is charged for access. Archiving, redistribution, or republication of this text on other terms, in any medium, requires both the consent of the authors and the University of Chicago Press.)
