1. Saurolophus. Her and Ducky's phenotype just matches the closest, even just based on the crest.
2. I really do love her characterization, what little there is overall, and The Big Freeze is both a fantastic sequel and a really great showcase of who she is. She's a saurolophus, but I'd argue that her strong motherly characteristics come from maiasarus, or the good mother lizard. She's certainly a lot warmer to all of the kids than Mrs. Maia is. Not only does she love her children, including Spike, unconditionally, but she's also willing to let Spike go with the other spiketails if that's what's best for him. She's unselfish in her love, despite the fact that she was clearly going through a lot in that movie, and, on that same note, she comforts Ducky rather than allowing her own feelings to get in the way. "He will always be part of your family" and such. I wish we heard her sing more. Really appreciate Tress McNeille's performance as her, and it sucks that she seems to have been replaced recently. Family on the whole is just a song that reinforces how family oriented she really is, in what I would call a very healthy way. And God, the ending with Spike falling through the ice is just beautiful and perfect and one of the most emotional moments in the franchise. Mama Swimmer doesn't hesitate to jump in after Spike and her just saying, "Of course. He's my boy" is just wonderful. I wasn't adopted myself, but I did grow up without any boy siblings, like how it seems to be with Ducky and her biological sisters, and I think it was always special to my mom when I brought over male friends. The moment almost brings me to tears just because of how special Spike must be to Mama Swimmer, and what that scene can mean to any family, but especially ones with adopted kids. Not to say she doesn't love all her children, but, well, Spike's her boy.
I wish more had been done with her overall, but what we got was really, really good.