Dear Hope and Jin
Barred spirals were indeed unexplained in any secular or classical evolutionary theory, and a major bizarre anomaly, until quite recently, the enigma resolved courtesy of the discrete field model (DFM).
http://vixra.org/pdf/1102.0016v3.pdf
I should of course say that although web archived at vixra and the RAS this is still not yet published in a mainstream journal as reviewers reject anything that may be conceived as different from the current ruling paradigm. In fact the DFM derives the observed effects of SR direct from a quantum mechanism, but it is none the less unfamiliar.
To explain; after AGN (disc) accretion and (quasar) jetting the re-ionized matter lies in a line, or splayed butterfly shape (from spiral jets) ave some 2,000 light years long (1M at M87).
Due to intrinsic rotation in space the central 'virial' radius starts to rotate (Google Hawk) propagating matter at the circumference and 'trailing the arms. Inside this the remains of the jet arms form the bar, which rotates bodily, or in 'lock step', just like all spirals. This is on a NEW perpendicular axis to the old galaxy, explaining They then evolve into a full spiral, merge into a disc, accrete into a lenticular as the AGN grows, and the cycle restarts. I recently posted to Singh's essay blog I think why the cycle seems to be around 10-12Gyr. There are good NASA shots of Centuarus A undergoing the rapid accretion and jetting process. (Previously thought o be a collision!)
There are many other anomalies explained by this.
Some papers with previous interpretations but good evidence here, the first of intrinsic rotation;
Parra, F.I., Barnes, M., Catto, P.J., RPCtr. Th.Phys. Ox. CCFE. N.Fusion. 2011. http://arxiv.org/pdf/1102.4613.pdf
Zoltan H. Jimenez R. Bernardire.M. Constructing the cosmic evolution of quasars from the age distribution of local early-type galaxieshttp://arxiv.org/PS_cache/astroph/pdf/0610/0610723v1.pdf
Wold,I. et al. Host galaxies of luminous quasars population synthesis of optical off-axis spectra.RAS Vol.408,Issue2,pp.713-730. http://adsabs.harvard.edu/abs/2010MNRAS.408..713W
Benton R, Metcalf, A. Constraints on Small-Scale Structures of Dark Matter from Flux Anomalies in Quasar Gravitational
Lenses http://arxiv/pdf/1007/1007.1599v1.pdf
DeBuhr, J., Quataert E., Ma, C.P., Galaxy-scale outflows driven by active galactic nuclei. MNRAS accepted. 30.10.2011
Martini ,P., Weinberg D.H.., Quasar Clustering and the Lifetime of Quasars 2001 ApJ 547 12 doi:10.1086/318331.
Porciani, C., Magliocchetti P., Norberg P., 2004 MNRAS 355 Issue 3, p1010-1030.
I do hope that is all enlightening. There is much more of course. Main paper now in review for 3rd time!
Best wishes
Please do also read my essay and comment. Thanks
Peter