Super spirals are the most massive star-forming disk galaxies in the universe(Ogle et al. 2016, 2019). We measured rotation curves for 23 massive spiralsand find a wide range of fast rotation speeds (240-570 km/s), indicatingenclosed dynamical masses of 0.6 - 4E12 Msun. Super spirals with mass in starslog Mstars / Msun > 11.5 break from the baryonic Tully-Fisher relation (BTFR)established for lower mass galaxies. The BTFR power-law index breaks from 3.75+/- 0.11 to 0.25 +/- 0.41 above a rotation speed of 340 km/s. Super spiralsalso have very high specific angular momenta that break from the Fall (1983)relation. These results indicate that super spirals are under-massive for theirdark matter halos, limited to a mass in stars of log Mstars / Msun < 11.8. Mostgiant elliptical galaxies also obey this fundamental limit, which correspondsto a critical dark halo mass of log Mhalo / Msun = 12.7. Once a halo reachesthis mass, its gas can no longer cool and collapse in a dynamical time. Superspirals survive today in halos as massive as log Mhalo / Msun = 13.6,continuing to form stars from the cold baryons they captured before their halosreached critical mass. The observed high-mass break in the BTFR is inconsistentwith the Modified Newtonian Dynamics (MOND) theory (Bekenstein and Milgrom1984).

The Galaxy And Mass Assembly (GAMA) survey has morphologically identified aclass of "Little Blue Spheroid" (LBS) galaxies whose relationship to otherclasses of galaxies we now examine in detail. Considering a sample of 868 LBSs,we find that such galaxies display similar but not identical colours, specificstar formation rates, stellar population ages, mass-to-light ratios, andmetallicities to Sd-Irr galaxies. We also find that LBSs typically occupyenvironments of even lower density than those of Sd-Irr galaxies, where ~65% ofLBS galaxies live in isolation. Using deep, high-resolution imaging from VSTKiDS and the new Bayesian, two-dimensional galaxy profile modeling code PROFIT,we further examine the detailed structure of LBSs and find that their S\'ersicindices, sizes, and axial ratios are compatible with those of low-masselliptical galaxies. We then examine SAMI Galaxy survey integral field emissionline kinematics for a subset of 62 LBSs and find that the majority (42) ofthese galaxies display ordered rotation with the remainder displayingdisturbed/non-ordered dynamics. Finally, we consider potential evolutionaryscenarios for a population with this unusual combination of properties,concluding that LBSs are likely formed by a mixture of merger and accretionprocesses still recently active in low-redshift dwarf populations. We alsoinfer that if LBS-like galaxies were subjected to quenching in a richenvironment, they would plausibly resemble cluster dwarf ellipticals.