That’s it.
Depends on what you mean by “taking care of”. Modern crocodilians take care of their young to some degree, and it’s reasonable to suspect early crocodiliformes in the Triassic may have done the same. I’m sure there are types of fish and maybe even arthropods that protect their young in some way after they are hatched/born. You may have to clarify a little.
Maiasaura was around in the late Cretaceous (65 million years ago) and looked after its babies.
Bees would seem to qualify.
One would have to say it is a silly question, fossil records are way to fague to tell. You could only extrapolate from contemporary animals’ behaviour.
I am obviously not asking to be told the unknown. “Silly” is your absolutist interpretation of the question.
Sorry, just saying it could be considered impossible to tell if any animal preceding mammals did or did not ‘take care’ of their offspring.
I would also be interested in knowing the smallest. Any microscopic parents out there?
No. They are not. You could, for example, read up about mom ‘n’ baby footprints found in Scotland
170 million years old for those of you keeping score at home.
I found some literature on it:
[quote=Parentage and the evolution of
parental behavior]
Multiple mating by females, which can reduce the relatedness of males to young, is widespread among vertebrate orders in which parental care occurs, including amphibians (Halliday and Verrell, 1984), reptiles (Devine, 1984), fishes (Constanz, 1984; Gross, 1979), birds (Birkhead, 1987; Birkhead and Mailer, 1992; McKinney et al., 1984; Westneat et al., 1990) and mammals (Ginsberg and Huck, 1989; MoUer and Birkhead, 1989).
[/quote]
But I was really curious about when and where parenting behavior evolved.
Since all extant mammals, including monotremes, marsupials, and placentals, produce milk, their last common ancestor probably did too, placing it perhaps in the late Triassic over 200 million years ago. Milk production in these forms can also be inferred by the presence of a separate milk dentition and a jaw structure conducive to suckling. However, parental care in mammals may have originated much earlier than that.
Adam and Eve.
Even in the Hebrew creation myth the birds and the beasts were created before Adam and Eve, so that’s certainly not it.
Hmm, do we have any evidence that any of the birds that predate the megazostrodon nourished and took care of their young much like most modern birds do? Any fossilized T-Rex nests? 
The Oviraptor’s name means “egg thief” because it was discovered over a nest of what was originally thought to be another dinosaur’s eggs. Recent discoveries have revealed more nests with Oviraptor embryos and it is now believed that the original Oviraptor found was a mother trying to protect her babies. This happened 70-80 million years ago. We wouldn’t have known the level of maternal care had we not found one over a nest.
But, as other posters have noted, this question really has no answer. For one, you need to define “taking care.” Does something that carries their offspring around with them but does not feed them after hatching count? What about species that make nests and fill it with food for their offspring but don’t stick around to see them hatch?
A fossil of Oviraptor has been found in which an adult dinosaur was apparently sitting on and incubating a clutch of eggs. Together with other fossils in which partly-grown young were found in nests (and therefore were probably being brought food by a parent), this strongly implies that at least some dinosaurs had parental care.
Both surviving lineages of the Archosauria, the crocodilians and birds, have parental care. There is also evidence for parental care in both major lineages of dinosaurs (ornithischians and saurischians), which were also archosaurs. This suggests that parental care might well have been an ancestral condition among the archosaurs. This group originated in the Permian, more than 250 million years ago.
As has been mentioned, fossil nests, tracks, and other kinds of evidence can allow us to infer that parental care took place in some groups.
Given that parental care is found in a wide variety of modern organisms, including fish, insects, crustaceans, and cephalopods, I would suspect that parental care originated well back in the Paleozoic, though positive evidence can be hard to come by.
Those behaviors are usually considered by biologists to be forms of parental care. Any kind of guarding of eggs or young qualifies, not just feeding them.